If you have really bad connection maybe this can take a long time?
10-15 minutes seems very strange though. Do you have a lot of chrome extensions activated?
Did you try running construct 3 in an incognito window to see if it's faster?
I have 100 down / 10 up for my internet, so i don't think that's the issue, especially since I tried running offline before. I disabled all extensions, and still get the same issue. Google Canary doesn't get the "ran out of memory" issue, but is still unusable slow.
Something odd though, when importing/opening my file, it'll load to 99.4%, then hang, occasionally getting that message that the tab is unresponsive, then about 10 minutes later it finishes loading.