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valis · 14th February 2010

If Aero is killing performance I recommend checking both the resource sharing with your graphics card's slot/IRQ and to see if you're using a card that is DX10 capable & has WDM 1.1 whql drivers... Win7 made significant improvements in the compositing engine used in Aero so now the GDI/GDI+ legacy path is no longer cpu bound (as it was in Vista) but gets composited on the card as well. The WDDM 1.0 > 1.1 move reduced 2d performance a bit to gain back a fair amount of ram overhead that WDDM 1.0/Vista had.

Unfortunately if you're having resource sharing issues, disabling aero 'seems' to fix it as the IRQ sharing is less of a problem, but you push all compositing back on the CPU.

Also fwiw, all of my Xeon machines have more than 4 addressing lines (due to typically having PCI-X & PCI bus lines in addition to more PCIe slots) and so IRQ sharing has been much less of an issue for me from the i860 (first P4 Xeons) on up...

14th February 2010	#12
valis Lives for gear Joined: Apr 2006 Location: Northwest USA Posts: 3,003	If Aero is killing performance I recommend checking both the resource sharing with your graphics card's slot/IRQ and to see if you're using a card that is DX10 capable & has WDM 1.1 whql drivers... Win7 made significant improvements in the compositing engine used in Aero so now the GDI/GDI+ legacy path is no longer cpu bound (as it was in Vista) but gets composited on the card as well. The WDDM 1.0 > 1.1 move reduced 2d performance a bit to gain back a fair amount of ram overhead that WDDM 1.0/Vista had. Unfortunately if you're having resource sharing issues, disabling aero 'seems' to fix it as the IRQ sharing is less of a problem, but you push all compositing back on the CPU. Also fwiw, all of my Xeon machines have more than 4 addressing lines (due to typically having PCI-X & PCI bus lines in addition to more PCIe slots) and so IRQ sharing has been much less of an issue for me from the i860 (first P4 Xeons) on up...