Firefox TLS Handshake hangs

Hey guys, I've been noticing just this week, huge TLS Handshake hangs on my Firefox browser at my office, which is on a Win7 Workstation, on a Server 2012 R2 domain, behind a SonicWall firewall. It's worked fine for years. However just this week I noticed these slowdowns, and I noticed today that if I stop the SomaFM music stream coming through Winamp, the TLS delays go away completely. Everything loads normally and fast. But when I start up the SomaFM music stream again, everything slows down.

Again I've been using both Firefox and listening to music streams through WinAmp (usually SomaFM) for years and never had any issues until this week. The stream is only 128 kbps so there definitely shouldn't be any bandwidth issues. My office uses Comcast/Xfinity business internet with 100+ Mbps download speeds. Any ideas what may be happening or what could have changed?