Devonthink has always been released with read-write disk images that are gzip compressed (now zip compressed).
It’s really bad now with Spotlight because the mds daemon tries to index everything on the disk images and totally hogs the CPU. That, combined with the update daemon writing changes to the disk image, while the Finder is trying to copy files from the image to the hard drive, completely brings the Mac to a crawl.
It’s a one-liner to convert a disk image to a read-only compressed image from Terminal,
hdiutil convert convert devonthink-uncompressed.dmg UDZO -o devonthink
UDZO is “UDIF z-lib compressed disk image,” as described in the man page for hdiutil. This way user’s don’t have to uncompress the disk image when they receive it, taking up a lot more room that the 7 MB download. It also ensures that users always have a pristine copy of the disk image on their hard drive.