[PROBLEM] Library loads very slowly on iPad using Safari

[swinokur]

Hey there,
I'm seeing an issue where the library is loading very slowing in Safari on iPad. 

Here's what I'm working with:
- library is 1728 folders, 24560 files
- thumbnail cache is 3223 files, 1612 are _sm.jpg 

iPad OS 15.2 on iPad Pro (10.5")
Wifi is 802.11ac (speedtest pulls about 400mbit to the internet, so I should be fine on the LAN!)

- Moode is on a rpi4

- Desktop performance (Windows, latest Chrome) is fine

- As I scroll the library downwards, instead of seeing text / thumbnails I see a blank page which will eventually fill in with information if I am patient. As I wait for this to fill I will also see other functions on the page stop (playback countdown timer, etc). It takes about 3-4 seconds before the blank area fills. (just counting out loud to measure)

I connected the iPad to a desktop safari machine to try to see if I could get some more data and saw this as I was scrolling:
   

- I notice that the browser is not loading the _sm.jpg tiles -- although the difference in size is apparently not that much:

Code:

pi@moode:/var/local/www/imagesw/thmcache$ ls -l bdf915803dd3ca11127d8bf4b711f986*
-rw-r--r-- 1 root root 1862 Jan 27 23:13 bdf915803dd3ca11127d8bf4b711f986.jpg
-rw-r--r-- 1 root root 1554 Jan 27 23:13 bdf915803dd3ca11127d8bf4b711f986_sm.jpg
pi@moode:/var/local/www/imagesw/thmcache$ ls -l 93d7d1b22328b7ed8447dd9b193d3ba4*
-rw-r--r-- 1 root root 1862 Jan 27 23:14 93d7d1b22328b7ed8447dd9b193d3ba4.jpg
-rw-r--r-- 1 root root 1554 Jan 27 23:14 93d7d1b22328b7ed8447dd9b193d3ba4_sm.jpg

I have tried regenerating the library and thumbnail caches and tags a couple times, as well as rebooting, etc.
thanks!