Problem with the New Core DLL Files

[zxwings]

I downloaded the the new core DLL files dated 3-13-2008, and made backups of the original files (il2_core.dll, il2_corep4.dll, il2setup.ini) before replacing them with the new ones. My experience with the new DLL files was not satisfacory at all - too much fps dropping; and the reason must have been that my hardware was old:
AMD Sempron 1.6GHz; 512 MB RAM; ATI Radeon 9600.

So I put the three backup files back into my IL2 folder. However, the game fps was as low as if I were still using the new DLL files.

Then, what's wrong? Is there anything I can do to restore my Il2 1946 to its original state?

Thanks for taking the time to read my post.