framerate drops when mouse pointer disappears

I have an interesting problem I'm not having much success resolving. When flying Briefing Time in FSX I lose about 5 fps when my mouse pointer disappears. If I move my mouse the framerate goes up again till my pointer automatically hides in 20 seconds or so. This does not occur with native FSX aircraft, but does occur with one of my other add-on aircraft. I have been trying to figure out how to prevent my mouse pointer from auto-hiding in the game, but have had no luck locating the applicable code in the game config file, aircraft config file, or in Nvidia card settings, or mouse settings. Any ideas on how to prevent framerate drop when pointer auto-hides or how to prevent pointer from auto-hiding in FSX would by greatly appreciated. Blindmelon