ODKcollect Slowdown, when more than 50 observations in a form (repeat + location Map)

I have a form with the following construction:

General Questions
Thirty fields to set the properties of where observations are made

Then a repeat group
selection of a plant
twenty questions related to the observation of the plant
widget location map

(no photo or other media)
no parallel csv file to fill a select,
but 2 long select present in the xml of the form (360 municipalities, 240 plants)

when I arrive around 50 and 70 points,
there is a slowdown in the fluidity of ODKcollect in general,
and significantly on the map widget which takes time to signal
(I remove the link with a network problem, GPS sensor and 4G data were ok on the smartphone at the time of the slowdown)

I save after each group via the floppy disk button.
To regain the fluidity of the start, I have to finalize the form, reopen it and go to the end to continue it.
There it is ok for 50s more points with a fluid entry.
One of my colleagues went up to 1200 observations on a same form, so it's possible to go far this way.

Is it a capacity limit by the application which in this specific case consumes too many resources? I think it's a form caching issue.
Is it my form that has a bad design?

I'm using ODK Collect v2022.3.6
The problem appears on all my device.
An example of the form
DevExemple.xml (63.5 KB)

Thank you for enlightening me on this point, or for your feedback on big form use.

Hi @Olivier_Poujade

Could you attach an xls version of your form? It is difficult to read xml.

Sorry, I'm writing the form directly in xml.
I only use the ODK Collect client from the ODK suite, I have never used XLSForms.