The DirectInput FPS Fix for the main game also works for the Expansion if the fix's dll is copied into the /FearXP folder. Worked for me on the GOG Version of FEAR Platinum.
Low Frame Rate in Extraction Point fixable
No Steam overlay.
Earlier this year I was able to play F.E.A.R with the Steam overlay and MSI Afterburner's Overly to look at performance. No longer can I. I tried everything. What gives? Google gives two results with no solutions.
Simple guess - try launching Steam AND/OR MSI Afterburner as administrator. As far as I remember - FEAR's exe starts with administrative rights, so Overlays from programs that don't have the same rights may not be able to hook into it.
There performance issues aren't limited to Logitech devices - I've had the frame rate to permanently drop to extremely low levels and I have never owned any Logitech peripherals.
In-game FSAA disables soft shadows. Nvidia control panel doesn't allow overriding program settings. I got AA working with the main game using Nvidia Inspector, but not with the expansions. The method used resulted in poor performance, the game was dropping below 60fps in the introduction sequence and runs far better in 4K (HUD is too small unfortunately) than in 1920 x 1080 with AA based on my testing. I did not enable supersampling unlike in the guide.
https://web.archive.org/web/20081210155127/http://www.projectorigincommunity.com/forum/archive/index.php/t-863.html / https://web.archive.org/web/20081018205848/http://lithfaq.com/forums/viewtopic.php?f=114&p=3167