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Why does loading a small pcap take lots of memory on 1 machine but not on another?


When I try and load a small capture (<5MB) Wireshark take over 2.5GB of ram and it takes a long time for the capture to appear on the screen. When my coworker loadss the same file on his machine running the same version of Wireshark it comes right up and utilizes little memory. Any ideas? Thanks for the assist!

asked 19 Jul '16, 11:35

kdonovan9's gravatar image

accept rate: 0%

edited 20 Jul '16, 08:05

cmaynard's gravatar image

cmaynard ♦♦

Did you try with identical Wireshark Versions and identical profiles? Profile settings can affect how Wireshark behaves, so even the same version may show differences.

Easiest way to test is to create a new (=default) profile on both machines, and load the trace again.

(19 Jul '16, 11:45) Jasper ♦♦

2 Answers:


I'd suggest comparing your preferences files. I wouldn't be surprised if you had something like TCP reassembly enabled while your colleague had it disabled. You can find your preferences file via Help -> About Wireshark -> Folders -> Personal configuration.

You could also look for any other differences between the machines, such as OS, 64-bit vs. 32-bit, etc. Compare Help -> About Wireshark information.

answered 19 Jul '16, 11:47

cmaynard's gravatar image

cmaynard ♦♦
accept rate: 20%


Another possibility we saw recently is that your ssl_keylog file has grown to a huge size. See bug 12501 for the history.

answered 20 Jul '16, 06:19

JeffMorriss's gravatar image

JeffMorriss ♦
accept rate: 27%

I have this same problem. I downgraded to 2.2.8 and removed my personal settings as well. My sslkeylog is 70M. I will have to see what I did to enable the use of that file and see if my slowness comes back.

(26 Jul '17, 10:47) garrywx

Ok that was it for sure. Recreated my problem after changing the setting under Pref->Protocols->SSL (Pre)-Master-Secret Log filename to point at my 70M file. I then deleted the file and performance is back to normal.

(26 Jul '17, 11:04) garrywx