diff --git a/rpcs3/Emu/Cell/PPUModule.cpp b/rpcs3/Emu/Cell/PPUModule.cpp
index 2607a428cd..4f44b56307 100644
--- a/rpcs3/Emu/Cell/PPUModule.cpp
+++ b/rpcs3/Emu/Cell/PPUModule.cpp
@@ -3,6 +3,7 @@
 
 #include "Utilities/bin_patch.h"
 #include "Utilities/StrUtil.h"
+#include "Utilities/address_range.h"
 #include "Crypto/sha1.h"
 #include "Crypto/unself.h"
 #include "Loader/ELF.h"
@@ -30,7 +31,7 @@ extern std::string ppu_get_function_name(const std::string& _module, u32 fnid);
 extern std::string ppu_get_variable_name(const std::string& _module, u32 vnid);
 extern void ppu_register_range(u32 addr, u32 size);
 extern void ppu_register_function_at(u32 addr, u32 size, ppu_function_t ptr);
-extern void ppu_initialize(const ppu_module& info);
+extern bool ppu_initialize(const ppu_module& info, bool = false);
 extern void ppu_initialize();
 
 extern void sys_initialize_tls(ppu_thread&, u64, u32, u32, u32);
@@ -1648,10 +1649,8 @@ void ppu_load_exec(const ppu_exec_object& elf)
 	}
 }
 
-std::shared_ptr<lv2_overlay> ppu_load_overlay(const ppu_exec_object& elf, const std::string& path)
+std::pair<std::shared_ptr<lv2_overlay>, CellError> ppu_load_overlay(const ppu_exec_object& elf, const std::string& path)
 {
-	const auto ovlm = idm::make_ptr<lv2_obj, lv2_overlay>();
-
 	// Access linkage information object
 	const auto link = g_fxo->get<ppu_linkage_info>();
 
@@ -1659,6 +1658,25 @@ std::shared_ptr<lv2_overlay> ppu_load_overlay(const ppu_exec_object& elf, const
 	sha1_context sha;
 	sha1_starts(&sha);
 
+	// Check if it is an overlay executable first
+	for (const auto& prog : elf.progs)
+	{
+		if (prog.p_type == 0x1u /* LOAD */ && prog.p_memsz)
+		{
+			using addr_range = utils::address_range;
+
+			const addr_range r = addr_range::start_length(::narrow<u32>(prog.p_vaddr), ::narrow<u32>(prog.p_memsz));
+
+			if (!r.valid() || !r.inside(addr_range::start_length(0x30000000, 0x10000000)))
+			{
+				// TODO: Check error and if there's a better way to error check
+				return {nullptr, CELL_ENOEXEC};
+			}
+		}
+	}
+
+	const auto ovlm = std::make_shared<lv2_overlay>();
+
 	// Allocate memory at fixed positions
 	for (const auto& prog : elf.progs)
 	{
@@ -1682,7 +1700,18 @@ std::shared_ptr<lv2_overlay> ppu_load_overlay(const ppu_exec_object& elf, const
 				fmt::throw_exception("Invalid binary size (0x%llx, memsz=0x%x)", prog.bin.size(), size);
 
 			if (!vm::get(vm::any, 0x30000000)->falloc(addr, size))
-				fmt::throw_exception("vm::falloc() failed (addr=0x%x, memsz=0x%x)", addr, size);
+			{
+				ppu_loader.error("ppu_load_overlay(): vm::falloc() failed (addr=0x%x, memsz=0x%x)", addr, size);
+
+				// Revert previous allocations
+				for (const auto& seg : ovlm->segs)
+				{
+					ensure(vm::dealloc(seg.addr));
+				}
+
+				// TODO: Check error code, maybe disallow more than one overlay instance completely
+				return {nullptr, CELL_EBUSY};
+			}
 
 			// Copy segment data, hash it
 			std::memcpy(vm::base(addr), prog.bin.data(), prog.bin.size());
@@ -1845,5 +1874,6 @@ std::shared_ptr<lv2_overlay> ppu_load_overlay(const ppu_exec_object& elf, const
 	ovlm->name = path.substr(path.find_last_of('/') + 1);
 	ovlm->path = path;
 
-	return ovlm;
+	idm::import_existing<lv2_obj, lv2_overlay>(ovlm);
+	return {std::move(ovlm), {}};
 }
diff --git a/rpcs3/Emu/Cell/PPUThread.cpp b/rpcs3/Emu/Cell/PPUThread.cpp
index 0f914b40db..3fcd0dc2f6 100644
--- a/rpcs3/Emu/Cell/PPUThread.cpp
+++ b/rpcs3/Emu/Cell/PPUThread.cpp
@@ -18,6 +18,8 @@
 #include "SPURecompiler.h"
 #include "lv2/sys_sync.h"
 #include "lv2/sys_prx.h"
+#include "lv2/sys_overlay.h"
+#include "lv2/sys_process.h"
 #include "lv2/sys_memory.h"
 #include "Emu/GDB.h"
 
@@ -117,8 +119,9 @@ const ppu_decoder<ppu_itype> g_ppu_itype;
 
 extern void ppu_initialize();
 extern void ppu_finalize(const ppu_module& info);
-extern void ppu_initialize(const ppu_module& info);
+extern bool ppu_initialize(const ppu_module& info, bool = false);
 static void ppu_initialize2(class jit_compiler& jit, const ppu_module& module_part, const std::string& cache_path, const std::string& obj_name);
+extern std::pair<std::shared_ptr<lv2_overlay>, CellError> ppu_load_overlay(const ppu_exec_object&, const std::string& path);
 extern void ppu_unload_prx(const lv2_prx&);
 extern std::shared_ptr<lv2_prx> ppu_load_prx(const ppu_prx_object&, const std::string&);
 extern void ppu_execute_syscall(ppu_thread& ppu, u64 code);
@@ -788,7 +791,7 @@ void ppu_thread::cpu_task()
 		}
 		case ppu_cmd::initialize:
 		{
-			cmd_pop(), ppu_initialize();
+			cmd_pop(), ppu_initialize(), spu_cache::initialize();
 			break;
 		}
 		case ppu_cmd::sleep:
@@ -2064,19 +2067,27 @@ extern void ppu_finalize(const ppu_module& info)
 #endif
 }
 
-extern void ppu_precompile(std::vector<std::string>& dir_queue)
+extern void ppu_precompile(std::vector<std::string>& dir_queue, std::vector<lv2_prx*>* loaded_prx)
 {
+	// Remove duplicates
+	std::sort(dir_queue.begin(), dir_queue.end());
+	dir_queue.erase(std::unique(dir_queue.begin(), dir_queue.end()), dir_queue.end());
+
+	const std::string firmware_sprx_path = vfs::get("/dev_flash/sys/external/");
+
+	// Map fixed address executables area, fake overlay support
+	const bool had_ovl = !vm::map(0x3000'0000, 0x1000'0000, 0x200).operator bool();
+	const u32 ppc_seg = std::exchange(g_ps3_process_info.ppc_seg, 0x3);
+
 	std::vector<std::pair<std::string, u64>> file_queue;
 	file_queue.reserve(2000);
 
-	// Initialize progress dialog
-	g_progr = "Scanning directories for SPRX libraries...";
-
 	// Find all .sprx files recursively (TODO: process .mself files)
 	for (usz i = 0; i < dir_queue.size(); i++)
 	{
 		if (Emu.IsStopped())
 		{
+			file_queue.clear();
 			break;
 		}
 
@@ -2086,6 +2097,7 @@ extern void ppu_precompile(std::vector<std::string>& dir_queue)
 		{
 			if (Emu.IsStopped())
 			{
+				file_queue.clear();
 				break;
 			}
 
@@ -2099,17 +2111,72 @@ extern void ppu_precompile(std::vector<std::string>& dir_queue)
 				continue;
 			}
 
+			std::string upper = fmt::to_upper(entry.name);
+
 			// Check .sprx filename
-			if (fmt::to_upper(entry.name).ends_with(".SPRX"))
+			if (upper.ends_with(".SPRX"))
 			{
+				// Skip already loaded modules or HLEd ones
+				if (dir_queue[i] == firmware_sprx_path)
+				{
+					bool ignore = false;
+
+					if (loaded_prx)
+					{
+						for (auto* obj : *loaded_prx)
+						{
+							if (obj->name == entry.name)
+							{
+								ignore = true;
+								break;
+							}
+						}
+
+						if (ignore)
+						{
+							continue;
+						}
+					}
+
+					if (g_cfg.core.libraries_control.get_set().count(entry.name + ":lle"))
+					{
+						// Force LLE
+						ignore = false;
+					}
+					else if (g_cfg.core.libraries_control.get_set().count(entry.name + ":hle"))
+					{
+						// Force HLE
+						ignore = true;
+					}
+					else
+					{
+						extern const std::map<std::string_view, int> g_prx_list;
+
+						// Use list
+						ignore = g_prx_list.count(entry.name) && g_prx_list.at(entry.name) != 0;
+					}
+
+					if (ignore)
+					{
+						continue;
+					}
+				}
+
 				// Get full path
 				file_queue.emplace_back(dir_queue[i] + entry.name, 0);
-				g_progr_ftotal++;
+				continue;
+			}
+
+			// Check .self filename
+			if (upper.ends_with(".SELF"))
+			{
+				// Get full path
+				file_queue.emplace_back(dir_queue[i] + entry.name,  0);
 				continue;
 			}
 
 			// Check .mself filename
-			if (fmt::to_upper(entry.name).ends_with(".MSELF"))
+			if (upper.ends_with(".MSELF"))
 			{
 				if (fs::file mself{dir_queue[i] + entry.name})
 				{
@@ -2125,11 +2192,20 @@ extern void ppu_precompile(std::vector<std::string>& dir_queue)
 							{
 								std::string name = rec.name;
 
-								if (fmt::to_upper(name).ends_with(".SPRX"))
+								upper = fmt::to_upper(name);
+
+								if (upper.ends_with(".SPRX"))
 								{
 									// .sprx inside .mself found
 									file_queue.emplace_back(dir_queue[i] + entry.name, rec.off);
-									g_progr_ftotal++;
+									continue;
+								}
+
+								if (upper.ends_with(".SELF"))
+								{
+									// .self inside .mself found
+									file_queue.emplace_back(dir_queue[i] + entry.name, rec.off);
+									continue;
 								}
 							}
 							else
@@ -2146,22 +2222,35 @@ extern void ppu_precompile(std::vector<std::string>& dir_queue)
 
 	g_progr = "Compiling PPU modules";
 
+	g_progr_ftotal += file_queue.size();
+
 	atomic_t<usz> fnext = 0;
 
-	shared_mutex sprx_mtx;
+	shared_mutex sprx_mtx, ovl_mtx;
 
-	named_thread_group workers("SPRX Worker ", utils::get_thread_count(), [&]
+	named_thread_group workers("SPRX Worker ", std::min<u32>(utils::get_thread_count(), ::size32(file_queue)), [&]
 	{
-		for (usz func_i = fnext++; func_i < file_queue.size(); func_i = fnext++)
+		for (usz func_i = fnext++; func_i < file_queue.size(); func_i = fnext++, g_progr_fdone++)
 		{
-			std::string path = std::as_const(file_queue)[func_i].first;
+			if (Emu.IsStopped())
+			{
+				continue;
+			}
 
-			ppu_log.notice("Trying to load SPRX: %s", path);
+			auto [path, offset] = std::as_const(file_queue)[func_i];
 
-			// Load MSELF or SPRX
+			ppu_log.notice("Trying to load: %s", path);
+
+			// Load MSELF, SPRX or SELF
 			fs::file src{path};
 
-			if (u64 off = file_queue[func_i].second)
+			if (!src)
+			{
+				ppu_log.error("Failed to open '%s' (%s)", path, fs::g_tls_error);
+				continue;
+			}
+
+			if (u64 off = offset)
 			{
 				// Adjust offset for MSELF
 				src.reset(std::make_unique<file_view>(std::move(src), off));
@@ -2173,9 +2262,15 @@ extern void ppu_precompile(std::vector<std::string>& dir_queue)
 			// Some files may fail to decrypt due to the lack of klic
 			src = decrypt_self(std::move(src));
 
-			const ppu_prx_object obj = src;
+			if (!src)
+			{
+				ppu_log.error("Failed to decrypt '%s'", path);
+				continue;		
+			}
 
-			if (obj == elf_error::ok)
+			elf_error prx_err{}, ovl_err{};
+
+			if (const ppu_prx_object obj = src; (prx_err = obj, obj == elf_error::ok))
 			{
 				std::unique_lock lock(sprx_mtx);
 
@@ -2188,19 +2283,64 @@ extern void ppu_precompile(std::vector<std::string>& dir_queue)
 					ppu_unload_prx(*prx);
 					lock.unlock();
 					ppu_finalize(*prx);
-					g_progr_fdone++;
+					continue;
+				}
+
+				// Log error
+				prx_err = elf_error::header_type;
+			}
+				
+			if (const ppu_exec_object obj = src; (ovl_err = obj, obj == elf_error::ok))
+			{
+				while (ovl_err == elf_error::ok)
+				{
+					// Only one thread compiles OVL atm, other can compile PRX cuncurrently
+					std::unique_lock lock(ovl_mtx);
+
+					auto [ovlm, error] = ppu_load_overlay(obj, path);
+
+					if (error)
+					{
+						// Abort
+						ovl_err = elf_error::header_type;
+						break;
+					}
+
+					ppu_initialize(*ovlm);
+
+					for (auto& seg : ovlm->segs)
+					{
+						vm::dealloc(seg.addr);
+					}
+
+					lock.unlock();
+					idm::remove<lv2_obj, lv2_overlay>(idm::last_id());
+					ppu_finalize(*ovlm);
+					break;
+				}
+
+				if (ovl_err == elf_error::ok)
+				{
 					continue;
 				}
 			}
 
-			ppu_log.error("Failed to load SPRX '%s' (%s)", path, obj.get_error());
-			g_progr_fdone++;
+			ppu_log.error("Failed to precompile '%s' (prx: %s, ovl: %s)", path, prx_err, ovl_err);
 			continue;
 		}
 	});
 
 	// Join every thread
 	workers.join();
+
+	// Revert changes
+
+	if (!had_ovl)
+	{
+		vm::unmap(0x3000'0000);
+	}
+
+	g_ps3_process_info.ppc_seg = ppc_seg;
 }
 
 extern void ppu_initialize()
@@ -2216,11 +2356,13 @@ extern void ppu_initialize()
 	{
 		return;
 	}
+	
+	bool compile_main = false;
 
-	// Initialize main module
+	// Check main module cache
 	if (!_main->segs.empty())
 	{
-		ppu_initialize(*_main);
+		compile_main = ppu_initialize(*_main, true);
 	}
 
 	std::vector<lv2_prx*> prx_list;
@@ -2230,20 +2372,68 @@ extern void ppu_initialize()
 		prx_list.emplace_back(&prx);
 	});
 
+	// If empty we have no indication for cache state, check everything
+	bool compile_fw = prx_list.empty();
+
+	// Check preloaded libraries cache
+	for (auto ptr : prx_list)
+	{
+		compile_fw |= ppu_initialize(*ptr, true);
+	}
+
+	std::vector<std::string> dir_queue;
+
+	if (compile_fw)
+	{
+		const std::string firmware_sprx_path = vfs::get("/dev_flash/sys/external/");
+		dir_queue.emplace_back(firmware_sprx_path);
+	}
+
+	// Avoid compilation if main's cache exists or it is a standalone SELF with no PARAM.SFO
+	if (compile_main && !Emu.GetTitleID().empty())
+	{
+		dir_queue.emplace_back(vfs::get(Emu.GetDir()) + '/');
+
+		if (const std::string dev_bdvd = vfs::get("/dev_bdvd/PS3_GAME"); !dev_bdvd.empty())
+		{
+			dir_queue.emplace_back(dev_bdvd + '/');
+		}
+	}
+
+	ppu_precompile(dir_queue, &prx_list);
+
+	if (Emu.IsStopped())
+	{
+		return;
+	}
+
+	// Initialize main module cache
+	if (!_main->segs.empty())
+	{
+		ppu_initialize(*_main);
+	}
+
 	// Initialize preloaded libraries
 	for (auto ptr : prx_list)
 	{
+		if (Emu.IsStopped())
+		{
+			return;
+		}
+
 		ppu_initialize(*ptr);
 	}
-
-	// Initialize SPU cache
-	spu_cache::initialize();
 }
 
-extern void ppu_initialize(const ppu_module& info)
+bool ppu_initialize(const ppu_module& info, bool check_only)
 {
 	if (g_cfg.core.ppu_decoder != ppu_decoder_type::llvm)
 	{
+		if (check_only)
+		{
+			return false;
+		}
+
 		// Temporarily
 		s_ppu_toc = g_fxo->get<std::unordered_map<u32, u32>>();
 
@@ -2261,7 +2451,7 @@ extern void ppu_initialize(const ppu_module& info)
 			}
 		}
 
-		return;
+		return false;
 	}
 
 	// Link table
@@ -2375,6 +2565,8 @@ extern void ppu_initialize(const ppu_module& info)
 	// Sync variable to acquire workloads
 	atomic_t<u32> work_cv = 0;
 
+	bool compiled_new = false;
+
 	while (jit_mod.vars.empty() && fpos < info.funcs.size())
 	{
 		// Initialize compiler instance
@@ -2581,7 +2773,7 @@ extern void ppu_initialize(const ppu_module& info)
 		// Check object file
 		if (jit_compiler::check(cache_path + obj_name))
 		{
-			if (!jit)
+			if (!jit && !check_only)
 			{
 				ppu_log.success("LLVM: Module exists: %s", obj_name);
 				continue;
@@ -2590,6 +2782,14 @@ extern void ppu_initialize(const ppu_module& info)
 			continue;
 		}
 
+		// Remember, used in ppu_initialize(void)
+		compiled_new = true;
+
+		if (check_only)
+		{
+			return true;
+		}
+
 		// Adjust information (is_compiled)
 		link_workload.back().second = true;
 
@@ -2651,7 +2851,7 @@ extern void ppu_initialize(const ppu_module& info)
 
 		if (Emu.IsStopped() || !get_current_cpu_thread())
 		{
-			return;
+			return compiled_new;
 		}
 
 		for (auto [obj_name, is_compiled] : link_workload)
@@ -2672,7 +2872,7 @@ extern void ppu_initialize(const ppu_module& info)
 
 	if (Emu.IsStopped() || !get_current_cpu_thread())
 	{
-		return;
+		return compiled_new;
 	}
 
 	// Jit can be null if the loop doesn't ever enter.
@@ -2742,6 +2942,8 @@ extern void ppu_initialize(const ppu_module& info)
 			}
 		}
 	}
+
+	return compiled_new;
 #else
 	fmt::throw_exception("LLVM is not available in this build.");
 #endif
diff --git a/rpcs3/Emu/Cell/lv2/sys_overlay.cpp b/rpcs3/Emu/Cell/lv2/sys_overlay.cpp
index cf7e6e3535..3c7609dc9f 100644
--- a/rpcs3/Emu/Cell/lv2/sys_overlay.cpp
+++ b/rpcs3/Emu/Cell/lv2/sys_overlay.cpp
@@ -12,9 +12,9 @@
 #include "sys_overlay.h"
 #include "sys_fs.h"
 
-extern std::shared_ptr<lv2_overlay> ppu_load_overlay(const ppu_exec_object&, const std::string& path);
+extern std::pair<std::shared_ptr<lv2_overlay>, CellError> ppu_load_overlay(const ppu_exec_object&, const std::string& path);
 
-extern void ppu_initialize(const ppu_module&);
+extern bool ppu_initialize(const ppu_module&, bool = false);
 extern void ppu_finalize(const ppu_module&);
 
 LOG_CHANNEL(sys_overlay);
@@ -42,7 +42,12 @@ static error_code overlay_load_module(vm::ptr<u32> ovlmid, const std::string& vp
 		return {CELL_ENOEXEC, obj.operator elf_error()};
 	}
 
-	const auto ovlm = ppu_load_overlay(obj, vfs::get(vpath));
+	const auto [ovlm, error] = ppu_load_overlay(obj, vfs::get(vpath));
+
+	if (error)
+	{
+		return error;
+	}
 
 	ppu_initialize(*ovlm);
 
diff --git a/rpcs3/Emu/Cell/lv2/sys_prx.cpp b/rpcs3/Emu/Cell/lv2/sys_prx.cpp
index 97954a6d0e..1f74cdaab0 100644
--- a/rpcs3/Emu/Cell/lv2/sys_prx.cpp
+++ b/rpcs3/Emu/Cell/lv2/sys_prx.cpp
@@ -17,7 +17,7 @@
 
 extern std::shared_ptr<lv2_prx> ppu_load_prx(const ppu_prx_object&, const std::string&);
 extern void ppu_unload_prx(const lv2_prx& prx);
-extern void ppu_initialize(const ppu_module&);
+extern bool ppu_initialize(const ppu_module&, bool = false);
 extern void ppu_finalize(const ppu_module&);
 
 LOG_CHANNEL(sys_prx);
diff --git a/rpcs3/Emu/System.cpp b/rpcs3/Emu/System.cpp
index bcbd9b375c..213dd2b274 100644
--- a/rpcs3/Emu/System.cpp
+++ b/rpcs3/Emu/System.cpp
@@ -66,8 +66,8 @@ atomic_t<u64> g_watchdog_hold_ctr{0};
 
 extern void ppu_load_exec(const ppu_exec_object&);
 extern void spu_load_exec(const spu_exec_object&);
-extern void ppu_precompile(std::vector<std::string>& dir_queue);
-extern void ppu_initialize(const ppu_module&);
+extern void ppu_precompile(std::vector<std::string>& dir_queue, std::vector<lv2_prx*>* loaded_prx);
+extern bool ppu_initialize(const ppu_module&, bool = false);
 extern void ppu_finalize(const ppu_module&);
 extern void ppu_unload_prx(const lv2_prx&);
 extern std::shared_ptr<lv2_prx> ppu_load_prx(const ppu_prx_object&, const std::string&);
@@ -1150,7 +1150,12 @@ game_boot_result Emulator::Load(const std::string& title_id, bool add_only, bool
 					ensure(vm::falloc(0x10000, 0xf0000, vm::main));
 				}
 
-				ppu_precompile(dir_queue);
+				if (Emu.IsStopped())
+				{
+					return;
+				}
+
+				ppu_precompile(dir_queue, nullptr);
 
 				// Exit "process"
 				Emu.CallAfter([]