What version of After Effects? What operating system?
Are both computers running the exact same version of After Effects (both with the most recent updates applied)? Are the preferences set to the exact same values?
I'm running CS5 (10.0.1.19) with the latest updates on both. I think I have all the settings exactly the same unless there are some that I haven't discovered.
I have the output settings all the same as well as multi-machine rendering turned off on both computers.
Do you have LZW compression turned on for one TIFF sequence and not the other? Are they both connected at the same network speed to the server drive?
Are those screen grabs from the local drives or the network drive? (Allocation tables could account for the size difference too) How big is each HD? How are they formatted?
How much RAM is reserved for other apps and the minimum RAM for each background renderer in your prefs. If they are both the same, then that's incorrect.
The differences could be accounted for by having an Alpha channel, even if it is fully opaque. Otherwise I would concur with the previous post - could be you8 have enabled compression on one machine. the differences in performance are another matter, but without some log files there is probably no way to unriddle that one. Could simply be some difference in an external DLL, could be slow drives, could be a motehrboard driver that is installed on one system but not on the other, could be the automatic CPU clock handling in combination with different energy saving settings. Who's to say?
I didn't have LZH compression on either machine. I just tried another quick pass and with LZH the file sizes came down to the 3,000KB range on both machines.
As a side note, Premiere spits out all kinds of error messages when trying to import the files with compression.
TIFFReadDirectory Warning "wrong data type 7 for XMLPacket; tag ignored." Maybe this is a post for the Premiere section.
Anyway, I am doing some testing on this on both machines now with logging enabled. I didn't have it turned on this last time around (except to track errors).
As far as I know, however, both settings were exactly the same.