Lastly the connect web app was pretty slow for me, and I just discovered why. The data loading is absolutely not optimized.
https://connect.garmin.com/modern/gear => click on a link to show a popup with all activities for a gear. In my example I use my shoes totaling 118 activities / 960km.
To show this popup, you need 4 data fields for every activity : Id, Name, Date, Distance. 472 fields in total .
But, the website loads a complete stack of 220 fields for each activity, resulting in a JSON response with 28 568 lines & 700Kb of data transferred.
Loading less data would immediately result in a more pleasant user experience (quicker response time, less compute on client side), and would even be a pretty significant saving for Garmin, as processor usage time & bandwidth are costly.
Just saying :)
erratum : the transfer size in "only" 50Kb, thanks to compression.