I made some new findings yesterday regarding how CPU clockspeed values affect performance in MGS (which I one of the games I've chosen for benchmarking). I guess some of you might already know this but for discussion's sake I'll be posting anyways. Btw, I'm using the actual .cia version of PCSX-ReArmed more than the forwarder, because it's easier to experiment that way. Normally, I'm on a very performance/speed-friendly configuration (with all relevant settings either enabled or disabled accordingly - except for audio, blending and lighting, which are always enabled). Also, I'm currently on a one week old nightly (I think). So now, let's talk about CPU clockspeed.
Normally when I tinker with clockspeed at all, I would try to find one particular value I can settle with so that the game could run in a most stable or uniform manner possible fps-wise when compared to how it runs at the default 50 (naturally, this would only happen if 50 is not good enough). For example, Spider-Man 1 is very volatile when set at 50: less demanding segments would run very smoothly but the drops and slowdowns are way too noticeable when the game gets really demanding; when set somewhere in the range 37-41, the framerate becomes much more stable and uniform, and the game much more playable, though naturally also a bit more janky (but still tolerable for me.)
According to my experience MGS is one of the more difficult 3D or graphically intensive games to get to run in a stable manner. At 50, cutscenes have tons of slowdowns (I often benchmark the opening submarine sequence), and in-game segments (meaning when you actually get to control Snake) also suffer from slowdowns when the game gets demanding. In my last efforts, when I play MGS I've usually set the clockspeed at 45 - merely as a compromise, so that cutscenes could benefit from some more frames while gameplay hopefully won't suffer too badly due to the decrease of only 5. Here's where it's problematic: MGS' in-game segments are really unfriendly towards underclocking. At 45, Snake mostly runs like snail.
Overall, MGS had always run like shit for me regardless of which clockspeed I tried. Until yesterday, when for the first time I actually tried to go above 50 (normally, I wouldn't dare doing that if a game already runs like shit at 50.) So I raised it to 60, and now in-game segments ran almost perfectly. Even in places when slowdowns had always happened when clockspeed was at 50 or lower. The cutscenes suffered from more slowdowns, sure, but I think now I can actually play the game if I want to (besides, I've always known that MGS cutscenes run way better with underclocking. For example, the opening submarine sequence runs very well at 30-31, with no discernible slowdowns.) My guess is that MGS might not be that demanding a game after all. Perhaps thanks to the overhead camera position, increasing clockspeed (when it feels rather counter-intuitive, at least for me) does make a real difference in performance and playability for a change in a 3D/graphically intensive game.
What config you use? Could you share it?