Improve mod loading performance on HDD by increasing read buffer size

[raspi-dude]

Is your feature request related to a problem? Please describe.
When loading mods on HDD-based servers, the mod loading process is slower than necessary due to small 4KB read buffers used during SHA256 hashing in TResourceManager.cpp (line 137).

Small buffers cause frequent small I/O operations which are inefficient on HDDs. Sequential reads with larger buffers would significantly improve performance.

Describe the solution you'd like
Increase the read buffer size from 4KB to a larger value (e.g., 1MB).

Impact

• No breaking changes, SHA256 hashes remain identical regardless of buffer size
• Faster mod loading, especially for large mod files
• Better HDD utilization with sequential reads (~10x increase in speed from my testing)

Files affected

• src/TResourceManager.cpp (line 137)

[WiserTixx]

I will be implementing this, increasing the default to 256kb. Along with this an env variable will be added that allows you to customize it for your hardware.