Desktop Window Manager High Memory Usage Caused by Excel

Like seemingly half the world, I have had issues with Desktop Window Manager using obscene amounts of memory and for the longest time I couldn't figure it out. I finally made the connection, all is fine until I open up two Excel (online App) Spreadsheets simultaneously. The memory usage goes from ~100MB to 1.6-2.0GB, and then never goes back down, even when Excel is closed out. I don't see this particular issue anywhere on the interwebs. Anyone have any idea what possibly could be causing this and what can be done?