Reading some of these recent posts about CPU/GPU utilisation, fps and vsync reminds me that I've been meaning for weeks to post about my recent observations on this, but I've been wanting to do some more testing first.
I'm not at the right PC now so can't provide full details, so I'll just state the basics, which may be relevant to this topic.
I got a big surprise after upgrading my CPU recently. It was coping really well with most tracks and I decided I didn't want to heat up my bedroom needlessly (!!) by having both the CPU and GPU running flat out and getting stupidly high fps (like 300). Thus, I decided to limit the frame rate (I had been running without any limit). I tried various rates, settling on 50ish fps and found I had massively reduced the wall-plug power consumption (IIRC, a ~100W drop!). Yay. I then decided to try vsync to see if I could spot the difference (absence of tearing) and indeed I could so I left vsync on.
A bit later I got the big surprise: I realised that when vsync was ON, the CPU was absolutely flat-out on the LFS thread. Bit of a WTF moment... I checked the power consumption and sure enough, it was stupidly high with vsync at 60 fps, and massively lower with frame rate SET to 62 fps (which gave me an actual fps of 60ish). I'm driving w/o vsync now
My planned-for testing was meant to work out if old versions of LFS did this (I was running H or maybe H2), and get some hard numbers on it, but that's the basic story already. I checked some older threads here, which had some mention of fps and vsync, but nobody observed what I've just mentioned (at least not that I found).
A quick bit of googling gave me some hints that vsync may be implicitly causing a busy wait (either in a game or the video driver), which seems a bit faily really but maybe there's just no better way, which would be tragic. If there is a better way, then perhaps LFS could use it. Or maybe my rig is just odd? (Win XP.)
NB: in the cases above, if thermal throttling does ever rear its head, it's more likely to happen with vsync on I guess (that's throttling on the CPU, not the GPU).