I tried it, and it's fantastic. I mean just really wonderful in a lot of ways. CAS and Buy mode catalogs and patterns load noticeably faster, and the game feels smoother as well.
I also noticed that a weird fps drop I normally get when panning over a certain pond is just gone. I do have a framerate cap in place, so that might be masking a smaller drop, but the normal stutter I'd see at the same time is mostly gone as well. The lot in question is the Delaney home lot in Dragon Valley, and I tested on both of the high water settings, with all other graphics maxed out except for high-detail lots.
This did not have any effect on my graphics card, either in temperature or workload.
A warning to anyone playing on a borderline system: this will increase the load on your processor, probably to a significant extent depending on the setting you use for this tool. So if the two cores that handle Sims 3 are already close to maxed out, or your CPU is already running hot, this tool is probably not for you. On the other hand, you can edit the accompanying text file to set a lower TPS: try 100 or less rather than the default 500. (The default Sims 3 setting is 30.) And use a hardware monitoring tool like CPU-Z or hwinfo to check temperatures and the load on each CPU core.