Opening capture files takes an exceedingly long time

Good morning. We've recently built a new server [Xeon E5-2440 hexcore+HT, 32 GB memory, 2 RAID arrays] running Windows 2012 and installed Wireshark [x64]. We've found, however, that opening .pcap files on this server is taking much longer than anticipated: over 20 minutes for a 188 MB .pcap file. Whereas on a comparatively shabby PC [Intel Q9550, 6 GB memory], the file opens in 2 minutes.

Can anyone think of reasons why capture-file loading would take so much longer on the server?

Thank you.