1. Google Chrome Version 47.0.2526.73 (64-bit) / Windows 7 SP1 / uBo 1.3.7
2. Default settings with "I am an advanced user" enabled. (All other extensions are disabled.)
3. Open: http://www.imdb.com/name/nm1111968/?ref_=tt_cl_t1
4. Go to "Releated Videos" section (scroll down)
5. Open one of the videos (it should popup on same page)
6. Wait until it loads, then close the popup (via X or ESC)
7. CPU usage will increase after closing the video and uBo extension will be unresponsive.

No problem with uBo 1.3.6