Speeding up Leaflet MarkerClusters

[stucork]

You may find this post helpful as it relates to search iterators

Performance Issues Working with Anvil Data Tables and Row Iterators

I will try my best to give a bit of insight here. First, an app_tables search call returns a lazy search iterator. I think they load on the order of 20 row objects at a time, and only load objects as needed. This is sometimes good, but when you iterate through an entire search iterator object, you load all the rows in batches and (I think) doing so with multiple back-end calls every 20ish rows. So, performance rapidly degrades, and unpacking a search iterator is expensive as you’re finding. It’…

You can check if its the iteration causing the slowness by removing the call to self.call_js and timing the iteration. I suspect you’ll find the same issue because iterating over 10,000 datatable rows on the client will result in several server calls to fetch data (a search iterator is lazy and fetches rows in batches).