It's tricky to improve performance with events. In my experience simpler is better and when doing something more complex to improve performance you also get more event and picking overhead which reduces overall improvement.
That said you'll probably want to measure it with wallclocktime to get a good idea if you're getting any improvements. "best first" might be a better choice than bi-directional or even going full A* might reduce the amount of cells to search through.
There are other things you can do too. One I tried is to not use the overlapping condition. Instead i populated an array with uid's so I could pick the neighbors directly so it wouldn't have to check all the instances if they're overlapping. That roughly made it twice as fast. I say roughly because it would take anywhere from 0.01 to 0.05, whereas before it was 0.03 to 0.08 seconds with my test. I can provide that capx if you'd like.
A next iteration could be to do all of it in an array and do no picking. That would give further improvements but would be harder to read. I'd imagine you may be able to half the time again, but that's just a guess. The only problem is it's less visual and more abstract at that point and if you change the tiles around you'd need to update the arrays accordingly.
The ultimate for speed would be to use js for most of it. Basically send the array or tile positions to some js code, then tell it a start and end tile. This is by far the most awkward and least flexible, but the performance improvement of calculating the path itself will be around 10x faster, or more with more tuning on the js side. This can be done with the browser object, since making a plugin would require a good design idea and take longer.
Another thing i've done elsewhere is to not do it in just one frame, but instead do it over multiple frames so it doesn't affect the framerate.