After an update I received on February 7th I started having so much freezing/stuttering of the frame rate I couldn't walk properly or even turn around. After fiddling around with the settings and putting them very low I could move around with much less freezing/stuttering than before. I also noticed that turning on the "basic shaders" adds back the same freezing/stuttering frame rates even on the lower settings. I had been using my original medium settings all this time without any problems. I could run, fly, drive and shoot very well.
I decided to do a reinstall and noticed that there were two 117mb SL Viewer programs installed. I deleted the more recently installed one, the desktop shortcut disappeared and I couldn't activate the older SL Viewer program. I then uninstalled that older program and reinstalled the viewer using the SL Viewer I had downloaded in November. I was still having issues with the frame rate and some time later I got an update that also downloaded a second 117mb SL Viewer program. This time I uninstalled the first SL Viewer, the desktop shortcut went away and I couldn't activate the second SL Viewer.
I then uninstalled the second viewer and also deleted the SL Viewer I had downloaded in November. I went to my dashboard and downloaded the SL Viewer and installed it. Some time after installing I got another update that downloaded a second 117mb SL Viewer.
Also, I had to adjust some shoes recently and, because I was on the lower settings, couldn't see the axis arrows until I put on the "basic shaders". I also had to cam very slowly so the frame rate wouldn't freeze. So now even adjusting objects is harder.