Previously using D3d-Windower, I've found that the framerate issues would go away on computers with them.
I'm not sure why or how this works, but it does occasionally. If you would like a copy of D3d-Windower-English that I've been using for years (without any problems of viruses or such), feel free to contact me and I'll send it to you. Several players are running the same one as me, no one has reported any issues (other than the program is a slight pain to set up. I may one of these days write a post on the forums with a link to it and how to get it running correctly.)