[TYPO3-dev] Slow BE since 4.5.x

[Mario Rimann]

Hi

We've the feeling that the BE in 4.5.x is way slower than it is in 4.4.x
due to the new fancy JS stuff. Especially loading the right column takes
longer as it should. And we're not experiencing this only in huge
installations, also smaller ones with just <200 pages.

There were some bug reports on this issue:
http://forge.typo3.org/issues/24990
http://forge.typo3.org/issues/25435

After my question "are we the only ones that see this as a problem",
some feedback arrived via twitter:
http://twitter.com/#!/awestbunk/status/56234851971514369
http://twitter.com/#!/rpflamm/status/56235898047692800
http://twitter.com/#!/psychomieze/status/56238003399569408
http://twitter.com/#!/andygrunwald/status/56242201528770560
http://twitter.com/#!/Alanin/status/56250038732599297
http://twitter.com/#!/designeon/status/56257552194863104

And there's even an extension that disables the spinning wheel loader image:
http://typo3.org/extensions/repository/view/noloadingmask/current/

Conclusion: There seems to be a real problem that bugs users around the
world.

Now the question is, what is needed to solve this issue? If it's a "no
one has time to implement the solution", we could put up a bounty for
the developer that get's the issue fixed. I personally consider this a
real blocker that should be treated like a bug. So it would be very
appreciated if the bug could end up in a 4.5.x maintenance release soon.

Can one of the BE developers/JS specialists explain where the real
bottleneck sits and how it could be solved? And/or what's needed to
solve the problem?

Cheers,
Mario