Reduced Skill Effect Duration should work on Slam Build up Time

That's the topic.

We know GGG does not want Slam Skills to be zoom zoom like POE1, but using that support gem instead of another more multiplier, is a fair tradeoff.
If you skill it on the passive tree, you have that downside with other skills you want to last longer.

Does not seem to be overpowered at all. Slams would still be relatively slow, but you're not over a second completely vulnerable anymore.

There is a difference between slams feeling impactful and clunky. Right now most feel they're on the clunky side. This could really fix the issue.

or maybe I'm alone on this one after all...

We already have skill cast +% which works on that.

There aren't many sources of it, but it works.