POSSIBLE SOLUTION!
Gduns and Ddouglass made a suggestion in the Beta Testers Forum that I think is the answer. My system was having no problems, and I changed my page file size and now I AM seeing the same problems you all are. When I changed it back, it is still exhibiting the slowness, so I'm signing off, rebooting and will test again. I suspect this requires rebooting after you change the setting.
Click Start > Settings > Control Panel > System (scroll down) > Advanced Tab > Performance section (click Settings button) > in Performance Options dialog, click Advanced > in Virtual Memory section, click Change button > Custom Size radio button > enter (this is a wild guess) 1.5x your total computer RAM in the first field and 3x in your second field > Click OK > OK > OK.
REBOOT YOUR COMPUTER before running Hoster again.