Hello my friends I know what a pain in the behind is to go from 60 fps to 2 and back and forth. Anyway I was looking for some answers online but there are few. Finally in a combinations of reading and messing with the files I found out this. This may or may not work for you. It surely worked for me. There still parts where the game lags but only for a couple of seconds but it is way better than before.
1st make sure that you have the latest version of java installed
2 make sure you have the latest software for your graphics card amd or nvidia bla bla bla
3 verify your game cache once more because there have been 3 updates small ones but there have been.
4 make your settings standard recommended but you can mess with this
5 use the dll that dan1337 posted for the remake here it is link just copy it where the game exe is
6 set the game to 30 fps recommended
and finally restart your pc after all this is done. When you start your game you will notice this change right away.
Is this for Revelations 2? I have tried different options and the best one for me was setting 30fps rather than 60fpr or auto(variable). You may also try to lower your AA and shadow detail. My specs are: Intel i3 ATI HD 5700 1GB 4GB RAM Windows 8.1 64bit (I hate it!)