Without actual exact system information and details about what footage you use, where it's stored etc. nobody can tell you much.
Yes, of course...sorry.
I work with an Imac 5K System El capitain vrs 10.11.1 intel i7 32gb ram. Materials are various format, photos in jpeg, video mxf, appleProRes, Hd, 2K, 3K.. But the most are photos.
Files are stored on Pegasus Promise 12TB thunderbolt.
Prj is stored on a GDrive 4TB thunderbolt.
The other machine is an oldest Imac, but the problem is the same even from a macbookpro.
Process: After Effects  Path: /Applications/Adobe After Effects CC 2017/Adobe After Effects CC 2017.app/Contents/MacOS/After Effects Identifier: com.adobe.AfterEffects Version: 14.2 (14.2) Code Type: X86-64 (Native) Parent Process: ???  Responsible: After Effects  User ID: 501 Date/Time: 2017-05-19 20:08:47.372 +0200 OS Version: Mac OS X 10.11.3 (15D21) Report Version: 11 Anonymous UUID: 2B68C285-616B-B8D3-CEEE-FD247DBC2A76
Time Awake Since Boot: 39000 seconds
System Integrity Protection: enabled
Crashed Thread: 0 Dispatch queue: com.apple.main-thread Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Exception Note: EXC_CORPSE_NOTIFY
Application Specific Information:
*** error for object 0x7fb41060b018: incorrect checksum for freed object - object was probably modified after being freed.
Global Trace Buffer (reverse chronological seconds):
66.859268 CFNetwork 0x00007fff8994fa5b TCP Conn 0x7fb448391560 SSL Handshake DONE
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