Changing the app install location will not help. The memory displayed is ram. When you open a program your phone loads its data from either the sdcard or internal memory into the ram. From there it runs the program.
When the system runs out of ram it clears out old tasks to make room for new ones, so the next time you 'open' sense, it loads from internal to ram. This is when it shows loading. Sense takes a lot of ram so its cleared out faster.
...not sure how to avoid it tho.. I use third party launchers (adw ex)