TP1200 very low

Hi

Configuration :
S71512 ET200SP
TP1200 comfort
TIA portal V17 updt 4

The HMI is very very slow

I mean, they can be slow sometimes, if you put 50+ faceplates on a screen, but only this screen is slow
Here, every screen is a disaster. Almost the same project has been running for 3 years, without worries....

I try :
- Restore by default the HMI
- Delete IM folder, recompile all
- Simulate on my PC, and it works normally (I understand that it's not a network problem)
- create a new "start screen" with only a int (increment by CPU), and still slow on that page
- delete template "navigation" on every screen, to have fewer element/screen, no changes
- delete all the scripts and their calls is too long, so I put all the script in 'comments
Anyway, I don't have script that "always run"
- CPU "Cycle load due to communication" at 50% (the max), no change
- I have no tag "cyclic continuous"
- change the RJ45 cable
- deconnect all others supplies on this network so I have HMI + CPU + PC only

- try on another TP1200, same thing (I understand problem come from TIA project)
- I am currently downloading update 5...but I have little hope.

In fact, if I stay on the start screen, the HMI have only one tag to display, and can't do it properly (sometimes every 500ms, sometimes 10+s)

So, I don't think it comes from :
- the network (work normally with simulation, and restrict network)
- from a surplus of tag (300 powertags, no one in continuous)
- from a surplus of script (27 script, doing nothing because I put in 'comments)
- from a surplus of element/screen (only one on the start screen)
What remains ?