diff --git a/Common/File/AndroidStorage.h b/Common/File/AndroidStorage.h
index 40ab19f1b..a9a88055d 100644
--- a/Common/File/AndroidStorage.h
+++ b/Common/File/AndroidStorage.h
@@ -73,7 +73,7 @@ inline StorageError Android_RemoveFile(const std::string &fileUri) { return Stor
 inline StorageError Android_RenameFileTo(const std::string &fileUri, const std::string &newName) { return StorageError::UNKNOWN; }
 inline bool Android_GetFileInfo(const std::string &fileUri, File::FileInfo *info) { return false; }
 inline bool Android_FileExists(const std::string &fileUri) { return false; }
-inline int64_t Android_GetRecursiveDirectorySize(const std::string &fileUri) { return -1; }
+inline int64_t Android_ComputeRecursiveDirectorySize(const std::string &fileUri) { return -1; }
 inline int64_t Android_GetFreeSpaceByContentUri(const std::string &uri) { return -1; }
 inline int64_t Android_GetFreeSpaceByFilePath(const std::string &filePath) { return -1; }
 inline bool Android_IsExternalStoragePreservedLegacy() { return false; }
diff --git a/Common/File/FileUtil.cpp b/Common/File/FileUtil.cpp
index 91c0aee6b..2de9d8959 100644
--- a/Common/File/FileUtil.cpp
+++ b/Common/File/FileUtil.cpp
@@ -324,6 +324,34 @@ std::string ResolvePath(const std::string &path) {
 #endif
 }
 
+static int64_t RecursiveSize(const Path &path) {
+	// TODO: Some file systems can optimize this.
+	std::vector<FileInfo> fileInfo;
+	if (!GetFilesInDir(path, &fileInfo)) {
+		return -1;
+	}
+	int64_t result = 0;
+	for (const auto &file : fileInfo) {
+		if (file.name == "." || file.name == "..")
+			continue;
+		if (file.isDirectory) {
+			result += RecursiveSize(file.fullName);
+		} else {
+			result += file.size;
+		}
+	}
+	return result;
+}
+
+uint64_t ComputeRecursiveDirectorySize(const Path &path) {
+	if (path.Type() == PathType::CONTENT_URI) {
+		return Android_ComputeRecursiveDirectorySize(path.ToString());
+	}
+
+	// Generic solution.
+	return RecursiveSize(path);
+}
+
 // Returns true if file filename exists. Will return true on directories.
 bool ExistsInDir(const Path &path, const std::string &filename) {
 	return Exists(path / filename);
diff --git a/Common/File/FileUtil.h b/Common/File/FileUtil.h
index ed0581b66..ae77f859a 100644
--- a/Common/File/FileUtil.h
+++ b/Common/File/FileUtil.h
@@ -79,6 +79,9 @@ uint64_t GetFileSize(const Path &filename);
 // Overloaded GetSize, accepts FILE*
 uint64_t GetFileSize(FILE *f);
 
+// Computes the recursive size of a directory. Warning: Might be slow!
+uint64_t ComputeRecursiveDirectorySize(const Path &path);
+
 // Returns true if successful, or path already exists.
 bool CreateDir(const Path &filename);
 
diff --git a/Core/FileSystems/BlobFileSystem.h b/Core/FileSystems/BlobFileSystem.h
index faab90004..f45576d6a 100644
--- a/Core/FileSystems/BlobFileSystem.h
+++ b/Core/FileSystems/BlobFileSystem.h
@@ -54,6 +54,8 @@ public:
 	bool RemoveFile(const std::string &filename) override;
 	u64 FreeSpace(const std::string &path) override;
 
+	bool ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) override { return false; }
+
 private:
 	// File positions.
 	std::map<u32, s64> entries_;
diff --git a/Core/FileSystems/DirectoryFileSystem.h b/Core/FileSystems/DirectoryFileSystem.h
index 9d8478d69..daf900a16 100644
--- a/Core/FileSystems/DirectoryFileSystem.h
+++ b/Core/FileSystems/DirectoryFileSystem.h
@@ -115,6 +115,9 @@ public:
 	FileSystemFlags Flags() override { return flags; }
 	u64 FreeSpace(const std::string &path) override;
 
+	// TODO: Replace with optimized implementation.
+	bool ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) override { return false; }
+
 private:
 	struct OpenFileEntry {
 		DirectoryFileHandle hFile;
@@ -159,6 +162,8 @@ public:
 	FileSystemFlags Flags() override { return FileSystemFlags::FLASH; }
 	u64 FreeSpace(const std::string &path) override { return 0; }
 
+	bool ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) override { return false; }
+
 private:
 	struct OpenFileEntry {
 		u8 *fileData;
diff --git a/Core/FileSystems/FileSystem.h b/Core/FileSystems/FileSystem.h
index 5df227dd1..87c87ae56 100644
--- a/Core/FileSystems/FileSystem.h
+++ b/Core/FileSystems/FileSystem.h
@@ -136,11 +136,11 @@ public:
 	virtual PSPDevType DevType(u32 handle) = 0;
 	virtual FileSystemFlags Flags() = 0;
 	virtual u64      FreeSpace(const std::string &path) = 0;
+	virtual bool     ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) = 0;
 };
 
 
-class EmptyFileSystem : public IFileSystem
-{
+class EmptyFileSystem : public IFileSystem {
 public:
 	virtual void DoState(PointerWrap &p) override {}
 	std::vector<PSPFileInfo> GetDirListing(std::string path) override {std::vector<PSPFileInfo> vec; return vec;}
@@ -161,6 +161,7 @@ public:
 	virtual PSPDevType DevType(u32 handle) override { return PSPDevType::INVALID; }
 	virtual FileSystemFlags Flags() override { return FileSystemFlags::NONE; }
 	virtual u64 FreeSpace(const std::string &path) override { return 0; }
+	bool ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) override { return false; }
 };
 
 
diff --git a/Core/FileSystems/ISOFileSystem.h b/Core/FileSystems/ISOFileSystem.h
index 0b8c00512..608fa444e 100644
--- a/Core/FileSystems/ISOFileSystem.h
+++ b/Core/FileSystems/ISOFileSystem.h
@@ -54,6 +54,8 @@ public:
 	int  RenameFile(const std::string &from, const std::string &to) override { return -1; }
 	bool RemoveFile(const std::string &filename) override { return false; }
 
+	bool ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) override { return false; }
+
 private:
 	struct TreeEntry {
 		~TreeEntry();
@@ -150,6 +152,8 @@ public:
 	int  RenameFile(const std::string &from, const std::string &to) override { return -1; }
 	bool RemoveFile(const std::string &filename) override { return false; }
 
+	bool ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) override { return false; }
+
 private:
 	std::shared_ptr<IFileSystem> isoFileSystem_;
 };
diff --git a/Core/FileSystems/MetaFileSystem.cpp b/Core/FileSystems/MetaFileSystem.cpp
index 173cf4a86..c726a87b5 100644
--- a/Core/FileSystems/MetaFileSystem.cpp
+++ b/Core/FileSystems/MetaFileSystem.cpp
@@ -500,12 +500,9 @@ bool MetaFileSystem::RemoveFile(const std::string &filename)
 	std::string of;
 	IFileSystem *system;
 	int error = MapFilePath(filename, of, &system);
-	if (error == 0)
-	{
+	if (error == 0) {
 		return system->RemoveFile(of);
-	}
-	else
-	{
+	} else {
 		return false;
 	}
 }
@@ -648,17 +645,36 @@ void MetaFileSystem::DoState(PointerWrap &p)
 	}
 }
 
-u64 MetaFileSystem::getDirSize(const std::string &dirPath) {
+int64_t MetaFileSystem::RecursiveSize(const std::string &dirPath) {
 	u64 result = 0;
 	auto allFiles = GetDirListing(dirPath);
 	for (auto file : allFiles) {
 		if (file.name == "." || file.name == "..")
 			continue;
 		if (file.type == FILETYPE_DIRECTORY) {
-			result += getDirSize(dirPath + file.name);
+			result += RecursiveSize(dirPath + file.name);
 		} else {
 			result += file.size;
 		}
 	}
 	return result;
 }
+
+int64_t MetaFileSystem::ComputeRecursiveDirectorySize(const std::string &filename) {
+	std::lock_guard<std::recursive_mutex> guard(lock);
+	std::string of;
+	IFileSystem *system;
+	int error = MapFilePath(filename, of, &system);
+	if (error == 0) {
+		int64_t size;
+		if (system->ComputeRecursiveDirSizeIfFast(of, &size)) {
+			// Some file systems can optimize this.
+			return size;
+		} else {
+			// Those that can't, we just run a generic implementation.
+			return RecursiveSize(filename);
+		}
+	} else {
+		return false;
+	}
+}
diff --git a/Core/FileSystems/MetaFileSystem.h b/Core/FileSystems/MetaFileSystem.h
index f980fc190..9a3b041c9 100644
--- a/Core/FileSystems/MetaFileSystem.h
+++ b/Core/FileSystems/MetaFileSystem.h
@@ -136,5 +136,19 @@ public:
 		startingDirectory = dir;
 	}
 
-	u64 getDirSize(const std::string &dirPath);
+	int64_t ComputeRecursiveDirectorySize(const std::string &dirPath);
+
+	// Shouldn't ever be called, but meh.
+	bool ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) override {
+		int64_t sizeTemp = ComputeRecursiveDirectorySize(path);
+		if (sizeTemp >= 0) {
+			*size = sizeTemp;
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+private:
+	int64_t RecursiveSize(const std::string &dirPath);
 };
diff --git a/Core/FileSystems/VirtualDiscFileSystem.h b/Core/FileSystems/VirtualDiscFileSystem.h
index 6c76d6b6f..0c1b6db87 100644
--- a/Core/FileSystems/VirtualDiscFileSystem.h
+++ b/Core/FileSystems/VirtualDiscFileSystem.h
@@ -52,6 +52,8 @@ public:
 	int  RenameFile(const std::string &from, const std::string &to) override;
 	bool RemoveFile(const std::string &filename) override;
 
+	bool ComputeRecursiveDirSizeIfFast(const std::string &path, int64_t *size) override { return false; }
+
 private:
 	void LoadFileListIndex();
 	// Warning: modifies input string.
diff --git a/Core/HW/MemoryStick.cpp b/Core/HW/MemoryStick.cpp
index 2efec86c7..964a00290 100644
--- a/Core/HW/MemoryStick.cpp
+++ b/Core/HW/MemoryStick.cpp
@@ -96,7 +96,7 @@ static void MemoryStick_CalcInitialFree() {
 	std::unique_lock<std::mutex> guard(freeCalcMutex);
 	freeCalcStatus = FreeCalcStatus::RUNNING;
 	freeCalcThread = std::thread([] {
-		memstickInitialFree = pspFileSystem.FreeSpace("ms0:/") + pspFileSystem.getDirSize("ms0:/PSP/SAVEDATA/");
+		memstickInitialFree = pspFileSystem.FreeSpace("ms0:/") + pspFileSystem.ComputeRecursiveDirectorySize("ms0:/PSP/SAVEDATA/");
 
 		std::unique_lock<std::mutex> guard(freeCalcMutex);
 		freeCalcStatus = FreeCalcStatus::DONE;
@@ -127,7 +127,7 @@ u64 MemoryStick_FreeSpace() {
 
 	// Assume the memory stick is only used to store savedata.
 	if (!memstickCurrentUseValid) {
-		memstickCurrentUse = pspFileSystem.getDirSize("ms0:/PSP/SAVEDATA/");
+		memstickCurrentUse = pspFileSystem.ComputeRecursiveDirectorySize("ms0:/PSP/SAVEDATA/");
 		memstickCurrentUseValid = true;
 	}