Performance
Compared to a standard UT2004 game, Fraghouse Invasion is a little more demanding, particularly on the visuals. Online play runs much better than offline because the server (where monster AI is executed) and the client (where the visuals are handled) remain separate. To help give an impression of what kind of performance to expect, we've created several "profiles" for you to compare your system to:
Low-end
Setup: Intel Pentium 4 HT 2.8 GHz, ASUS P4P800-VM, 1GB RAM (4x256), Sapphire Radeon9600XT (256MB)
Detail Settings: 1280x1024, everything maxed out, no AA or AF
Framerates: 50-70 on average map with 8 bots, dips as low as 20 with monsters on screen
Framerates with bloom: 30-50 on average map with 8 bots, dips as low as 10 with monsters on screen
Middle-end
Setup: AMD Athlon XP 2800, MSI KT4 Ultra, 2GB DDR333 RAM, Soundblaster Live!, nVidia Geforce 7600GT
Detail Settings: 1280x1024, everything maxed out, 4xAF and 2xAA
Framerates: 100-120 on average map with 8 bots, dips as low as 80 with monsters on screen
Framerates with bloom: 90-105 on average map with 8 bots, dips as low as 60 with monsters on screen
Upper-middle-end
Setup: Intel C2D E6320 (1.86Ghz), Gigabyte P35-DS3L, 2GB PC6400, RT HD Audio, 8600GTS (256MB)
Detail Settings: 1280x1024, everything maxed out (No AA or AF)
Framerates: 100-150, dropping to 30-45 during the waves.
Framerates with bloom: 90-120 on average, dropping to 60 during the waves
Upper-middle-end 2
Setup: Intel P4 3Ghz (3 - 3.3Ghz) w/ HT, ASUS P4C800-E, 2GB (PC3200), XFi Platinum FPS Ed, X1950Pro (256MB)
Detail Settings: 1920x1200, everything maxed out (No AA or AF)
Framerates: 50-120, dropping to 20-60 during the waves
Framerates with bloom: 30-50 on average, dropping to 20 during the waves
High-end
Setup: Intel Core 2 Duo E6300 (at 2.1GHz), ASRock 4CoreDual-VSTA, 2GB PC5400 RAM, Creative X-Fi Music, nVidia 8800GTS (320MB)
Detail Settings: 1280x1024, everything maxed out, 16x anisotropic filtering, 16x antialiasing
Framerates: 250-300 on average map with 8 bots, dips as low as 120 with monsters on screen
Framerates with bloom: 120-200 on average map with 8 bots, dips as low as 60 with monsters on screen
High-end 2
Setup: Intel Q6600 (2.4Ghz), Gigabyte P35-DQ6, 2GB PC6400, XFi Platinum FPS Ed, 8800GTS (640MB)
Detail Settings: Max at 1920x1200 (No AA or AF)
Framerates: 300+, dropping to 80-160 during the waves
Framerates with bloom: Same as normal framerates (640MB framebuffer copes with no performance decrease)
As a general guideline, you should be absolutely fine if you have a fairly modern processor and something like an nVidia 6800GT graphics card. The 7600GT (a great middle-price solution) can run FHI with more than acceptable framerates.