Beware though that there are some extensions, eg Podium, which will install into the Program Datatree by default AND DOES NOT WORK if you try to install it into the Users...App Datatree.

@tig said: It is known that SketchyPhysics is implicated in ill-advisedly messing with some native base classes like 'Group', but I've never heard of it messing with DCs before Other 'rogue tools' include DrivingDimensions, SunPosition, Matchbox and some versions of Podium... I can now confirm that SketchyPhysics3 caused the problem. The problem was corrected after removing the sketchyphysics.rb and sketchysolids.rb files from the SU plugins directory on two different machines and operating systems: TOSHIBA TECRA, WINDOWS XP PROFESSIONAL SP3, 32 BITS APPLE PRO 8 NUCLEI, WINDOWS 7 PROFESSIONAL, 64 BITS (BOOTCAMP INSTALLATION) I hope this may be useful if someone runs into the same problem.

@unknownuser said: i'm on a quad mac and do not have the slowness either.. SU is very responsive until i get into very high polycount territory.. when you say it runs slowly, are you talking only about how long it takes to open a file or are there other issues as well? most of my skps open instantly (no noticeable pause at all).. files with a lot of textures/poly (25MB+) take maybe a second or two to open.. you may have something set up weird or SU may be running normally.. it's hard to tell because i'm not quite sure what you mean by 'slow' I may well have something wrongly setup. It took me quite a while to discover that the Open GL option "Use fast feedbaback" was troublesome with the nVidia video card on the Windows machine. But stopwatch in hand, importing a 76 KB skp component into a 34 MB drawing takes 30 seconds on the Mac against 7 seconds on the laptop. Opening the 34 MB file on the Mac is faster than on the Windows machine (40 sec, against 50 sec), probably due to the newer, faster hard disk. Movement lag when orbiting is about the same on both machines. And sometimes drawing on the Mac seems to get somewhat sluggish (no measurements yet). I am evaluating the possibility of using large single files for projects, originating any number of views and cuts. Modifications of the base file can be automatically updated in Layout, avoiding a lot of work and the possibility of errors.