How can I shrink my 12GB pagefile.sys?

You can manually limit the pagefile size by performing the following steps:

1. Click on the Start button.
2. Right click on Computer.
3. Select Properties
4. Click on Advanced system settings on the left.
5. Click on the Settings button under the Performance group.
6. Select the Advanced tab of the Performance Options window.
7. Click on the Change button.
8. Uncheck Automatically manage paging file size for all drives.
9. Select the C: drive in the list.
10. Check the Custom size radio button.
11. Enter the Initial and Maximum sizes you want to use. I would recommend 4096 MB for the Initial and 6144 MB for the Maximum.
12. Click OK on the Virtual Memory dialog.
13. Click OK on the Performance Options dialog.
14. Click OK on the System Properties dialog.

You can force a Virtual Memory file size by:

1. Left click on 'Start'.
2. Right click on 'PC'.
3. Left click on 'Properties'.
4. Left click on 'Advanced system configuration'.
5. If needed, left click on 'OK'.
6. Select 'Advanced options' tab.
7. Left click on 'Configuration' inside 'Throughput'.
8. Select 'Advanced options' tab.
9. Left click on 'Change' inside 'Virtual memory'.
10. Edit your preferences.
11. Close all the opened windows by accepting.