Safari (10.0.3) memory leak

Noticed today, Safari occasionally starts eating up memory until it reaches tens of gigabytes of memory used and freezes the whole system. Both cases when this happened, the trigger was starting watching a video on youtube (using the HTML5 player). In Activity Monitor, no particular tab process shows high memory usage (not even the youtube ones), only the main Safari process. Closing tabs one by one does not stop the leak, even when all tabs are closed the main process continues gobbling up the memory. I have no extensions enabled (I disabled AdGuard after the first leak). I sampled the process during the second leak, but I'm not skilled enough to read the output (http://pastebin.com/MTxmEAQ4) . Any ideas how to fix this? I hate going back to Chrome, but this is unacceptable. Thanks, O