I do not have the prescription writer slowness that you complain of and I am using 6.0.10. I have Win 7 Pro.
My entire program slowness started this summer, after a year of using 5.0.29. I looked forward to the 6.0.9 upgrade, only to find it did not fix my slowness. I only used 6.0.9 < 1mo before asking tech support for help. I think the prescription writer improved with 6.0.10.
BTW, I have heard for years that Allscripts is not a great program for eprescribing.