In no particular order (top of my head and mostly considering the desktop Windows one)

  - The history (scroll up) takes a lot to load (this is on 300mbit up/down and fast processor)
  - html content in the chat totally hogs the processor
  - Attachments takes forever to open internally. Not so large files like 4-5MB of log pretty much wreck it
  - upload is hilariously slow (again 300mbit up/down)
  - loading in browser requires an explicit login to microsoft account to open, instead of a generated link that actually works (to add some salt, my company requires 2FA for the MS login)
  - audio quality issues, 'intelligent' (echo blocking algorithm kicks in wherever it wants), call drops. Esp. bad in group calls
  - 'teams' chat gotta be a joke with each post forming its own thread, and you'd need to click to answer the proper one. Close to unusable feature that bears the name of the product
  - Video sharing has a massive lag on screen sharing both on visual and startup time
  - Blurred background algorithm is a massive flicker and it really resents people with green (t-)shirts
  - Calling the phone, instead the desktop while working on the desktop. (Half of my team uses phone version as it's less buggy)
  - One more: if you don't login the phone app, it will remind you to login every 3hours - until it gets uninstalled....

I can rant for at least 45minutes about it... and it's the 'default' chat application the company uses for years (along with Lync/Skype for business before) and I use it as my 'main' chat application.

Some points to add:

  - As soon as I start a Videocall, the rest of the Application is almost completely unusable
  - The Application uses 500MB of RAM after it has been idling with one message received in the last hour

I have 32GB of RAM and a dedicated video card, so it's passable. But yeah, resource wise - calling it 'inefficient' is putting mildly.

> 'teams' chat gotta be a joke

I've never understood this either. What is the purpose of the Teams tab? Why doesn't it show up where all the other conversations happen? It doesn't make any sense to me.

> The history (scroll up) takes a lot to load (this is on 300mbit up/down and fast processor)

that's not my experience, especially with a much worse connection. Maybe I live closer to the server?

> 'teams' chat gotta be a joke with each post forming its own thread, and you'd need to click to answer the proper one. Close to unusable feature that bears the name of the product

Interestingly, I like this feature: it's different from a group chat where all discussion are mixed together, each subject has its own thread, so it's easier to follow. And each thread can be ignored

On a lower-end "business" laptop, every interaction is painfully slow. For example, it takes 2 seconds just to switch to a different chat, you can see the redraw happening in real-time...

What about Teams running against a Lync server where you can only establish chats with internal users, and chat with external users is available only through a fake meeting set up in outlook? And where the 1to1 video calls start in skype 4 business instead of teams.

Plus when running multiple instances the call goes to the first instance

What about hiding previous communiques? I have a long list of psuedo-named meeting chats (5 months worth) that are just aggregating on the left hand side. Hide doesn't work. Thanks teams.

- No choice of download directory in their app

I attempt to use the Linu client on Fedora about once a month. Either the video doesn’t work or the sound has a problem, or both.

Meanwhile, Zoom works daily without issue.