Might actually be an issue with my specific install of Windows 10, but nonetheless
Been meaning to play this game for some time, so downloaded it on a whim some time ago and immediately ran into an issue - the moment gameplay starts my FPS locks to ~19-20 despite being unlocked before, no matter the resolution or graphical settings, while still being unlocked in the menus
Happens on every build that I've tried, both Steam version (1.0.314.0, compiled 23rd Feb 2006) and Retail (1.0.320.0, compiled 06th Mar 2006), even in demo
I've tried the general DInput fix, specific Condemned set of fixes, 4 GB patch, compatibility settings, physically disconnecting all Logitech hardware, reinstalling graphics drivers.
Happens with regular ol' DirectX 9, DXVK, dgVoodoo 2. For a moment there thought that this might be happening because I have a Creative sound card and maybe the game is trying to do something with EAX or whatever, but disabling the device or using DSOAL with OpenAL Soft also didn't help.
After several days of messing with everything described above and config file, it turned out that disabling the entire HUD by setting "XUIUseOldHUD" to 0 in a config file mitigates whatever issue was happening and unlocks the framerate, too bad that it's not an actual solution for someone who hasn't played the game before, like me
For a laugh tried to run it inside an XP VM and the issue wasn't there, but for obvious reasons performance was suboptimal
Worked seemingly fine with DXVK under Linux until I played for two more minutes and realized that there are other graphical issues present
Windows 
Linux 
(also notice the runtime font substitution as opposed to using a premade font atlas, neat)
anyways @ monolith open source the entirety of lithtech jupiter ex already thanks
alternatively if you're a dev or somehow otherwise obtained the entirety of Condemned code my twister DMs (or cohost asks here actually, also anonymous) are open if you want to send it to me 🥺