The performance improvement with this tool is significant for me, it makes opening menus while in VR tolerable. From what I can tell, you do need to run the vam-storebuilder every time that you add vars to get them into the cache.
Two bugs I've noticed:
1. When opening the clothing menu on an person atom, the active filter is reset to "Active" and the list is refreshed. The expected behavior is that the active filter would remain on the previous value and that the list would not be refreshed. Often times you want to test different clothings and you might disable a piece of clothing and close the menu and when you re-open the menu you want that clothing to still be in the menu even though it's disabled, but if you refresh the menu it gets removed from the active list since it's unchecked.
2. When browsing clothing with filter set to All Items, sometimes the Customize buttons disappear. Pressing refresh gets them back. Expected behavior is that the customize button is always visible for all clothing items.