---Space Laser--- As @GoldenHeart points out in
his meta thread; after being active for several minutes, the
Bifrost begins to warp space and pull in stars. Thor, of course, breaks the Bifrost at the end of Thor 1. Fenrir and Hulk also take large chunks out of it while fighting in Ragnarok.
There might be some arguments about the exact nature of this singularity. But whatever it is, it can't generate more energetic effects (ie moving stars) than the event that created it. So it's safe to say that, over the course of the singularity's formation, the Bifrost channels the grand total GBE of the moving stars.
tl;dr: Stars < Singularity < Biforst, regardless of what the singularity is.
The bridge's durability would be something like the X * Y / Z = Bifrost durability in joules per second
X = Smallest star GBE
Y = Number of stars
Z = Time the Bifrost beam was active
The Bifrost is active for 390 seconds. I can't find a clip on YT. They all start right after Thor arrives, a couple minutes after Loki powers up the beam. It's also near impossible to get an
exact count on these stars - especially with the debris flying around in frame - but my recounts average around half-a-dozen in motion.
GBE of the smallest star = 9.998 ninatons * 6 / 390 =
206.85 tenatons/second (Large Planet level) Add as many stars as you want. You'd need 390 to get out of Large Planet level (ya know, cause division), and there clearly aren't nearly 400 stars in motion.