Well I just put together this low spec test system
System POS: Desktop case (That is, spread out over a desktop )
AMD Athlon 64 3000+ 2GHz
1 GB RAM
Maxtor 40GB HDD
XP Home SP3
Sapphire Radeon X1550 ATI 512MB DDR2 AGP
ATI Catalyst Display Driver Version 9.11
Editor opening : 4.5 secs
The only standard map I could open was the tunnels anything else caused the editor to exit.
Tunnels.sbx : opened in ~3 secs
With everything turned on or set to high that is:
Running the flythrough.lua I got between 7 and 12 FPS.
Editor when closed exited almost instantly.