SU 8, a 32 bit application, on Windows 7 x64 can run slow

[mac1]

Quote form Mark Russinovick “ Pushing the limits of Windows: Physical Memory” 21 Jul 2008.
“While 4GB is the licensed limit for 32-bit client SKUs, the effective limit is actually lower and dependent on the system's chip-set and connected devices. The reason is that the physical address map includes not only RAM, but device memory as well, and x86 and x64 systems map all device memory below the 4GB address boundary to remain compatible with 32-bit operating systems that don't know how to handle addresses larger than 4GB. If a system has 4GB RAM and devices, like video, audio and network adapters, that implement windows into their device memory that sum to 500MB, 500MB of the 4GB of RAM will reside above the 4GB address boundary, as seen below”.

For x64 systems SU gets a full 4GB( Large address aware ) memory ,but because SU runs as 32 bit processes the video card etc. still gets mapped below this 4GB SU address limit as noted in the above quote. Therefore, if you have very large video memory like seen in some post ( IE two displays at 1 GB each. They have reported very slow performance.) you may very well have less memory vs what is usually allocated for SU ( 2GB with 4GB RAM installed) on a x32 system with normal video memory ( 200 to 500MB)

The SKU limit of W7 x64 for installed RAM can be as low as 2GB and up to 18Gb? ( The server class is higher) with ,I would guess, most users at 4GB.
If one wants to see their system memory use run devmgmt.msc, change the view to resource by connection, select memory and then expand. One will note your video, along with other items, uses system memory. Using the calculator in the accessories drop down allows easy conversion form hex to dec. and one can calculate the actual MB value allocated.

**The contention is be careful when you configure a x64 system and be aware of memory allocation if large video memory is planned and 32 bit apps like SU are used. Also see this link http://www.sevenforums.com/hardware-devices/5816-windows-7-64-bit-ram-issue.html for some possible x64 setup help help.

Correction / addition comments welcomed / solicited**