As there is no real gameplay, you'll want to get the achievements quickly.
Normal mode is extremely slow, so you want to do the farm mode that pops up randomly.
Now, if you enter normal mode and try to Esc to the main menu, the game will crash.

What you want to do is click at least one window to close it so you will get at least 1 score. Now you can exit to main menu and the game won't crash. Repeat until you enter farm mode.

In Farm Mode, ~200 windows will appear across 60 seconds. You can use an autoclicker for quick progress. You can even do something else in the meantime and come back to autoclick the windows once the timer is almost up.

In order to close a window, you have to click in the middle of it. If you try to click on the cross near the top right corner, actually nothing happens. (With autoclicker just rotate cursor around screen.)

Upgrade Upgrade Points first to about 16x, then score to about 12x. Now you can spend the rest of the points on Sum Total and you should be able to get everything at roughly the same time. (Achievements end at 20K Upgrade Points, 40K Score and 50K closed windows.)

Congratulations on the 100%!