I also get slow down with the beta on this rig.
Meduim Galaxies.
Nine players
I still think the slowdown is caused by some of the ship jewelry, because my computer frap rates crash when i try to apply specific ones on my ships, so i figure if any of the comps are using jewelry that create that to happen on just a single ship, multiple ships could be the reason for the massive slowdown. The slowdowns only occur after attack ships are begining to be produced. Who knows

I try to play with AA on 2, but i still experience this problem when lowering every requirement, and forced to play the game in tactical mode.
DirectX Version: DirectX 9.0c (4.09.0000.0904)
Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_gdr.050301-1519)
Languages: English (Regional Setting: English)
BIOS: BIOS Date: 12/13/05 11:07:57 Ver: 08.00.09
Processor: Intel(R) Pentium(R) 4 CPU 3.20GHz (2 CPUs)
Physical Memory: 1024MB RAM
Page File: 255MB used, 2206MB available
Windows Dir: C:\WINDOWS
Display Info
Display device 1:
Device Name: \\.\DISPLAY1
Card Name: NVIDIA GeForce 6800
Manufacturer: NVIDIA
Chip Type: GeForce 6800
DAC Type: Integrated RAMDAC
Key Device: Enum\PCI\VEN_10DE&DEV_0041&SUBSYS_A3433842&REV_A1
Display Memory: 128.0 MB
Current Display Mode: 1280 x 1024 (32 bit) (72Hz)
Monitor Name: Plug and Play Monitor
Monitor Max Resolution: 1600,1200
Driver Name: nv4_disp.dll
Driver Version: 6.14.0010.9371
Driver Date: 10/22/2006 12:22:00
DirectX Acceleration Enabled: Yes