Also, your stills may be n the large size, you could drop in PhotoShop and downsize them a bit to like 2500 on the long size. This would still allow for moves.
Make sure your stills are 72 DPI and RGB.
When the edit is locked/down/final I would change the sequence compressor to Prores HQ OR 10 bit uncompressed, re render all final.
Export using "Current Settings"
drop that file into your compression program for delivery.