Dash: Dropdown selector with a long list is very slow

[jamestwebber]

This might be a plotly issue rather than a Dash issue, I'm not sure.

We've built some dropdown selectors that have very long lists of options (several thousand), and trying to use them is very slow. I couldn't figure out where the options are stored, but I did confirm that it's not going back to the server at least (because I can stop the server and still select a new item).

If there's a way to make the widget more responsive at the expense of memory that would be well worth it for us.

[chriddyp]

Here's a simple example with 1000 items:

Which seems pretty fast. There might be something else that's going on here that would make it slow. Could you share a simple but slow example?

[jamestwebber]

"Very slow" might have been a slight exaggeration, but I am impatient (and the users are more impatient). With ~23000 items there's a couple second delay between clicking and getting a list, and there's also a delay between typing and getting any feedback:

[chriddyp]

Ah yeah, different story with 23,000 items. That _is_ slow! It looks like we could maybe swap out the dropdown with https://github.com/bvaughn/react-virtualized-select/ to make it faster....

[chriddyp]

Just tried out react-virtualized-select on 10k points and it froze 😕

[chriddyp]

ah but maybe https://github.com/bvaughn/react-select-fast-filter-options

[chriddyp]

woohoo! now that's what i'm talking about:

[chriddyp]

OK, published it to a pre-release channel. @jamestwebber - could you try it out?

pip install dash-core-components==0.10.0rc1

[chriddyp]

It works pretty well for 50k options, but starts to bog down at 100k options

[jamestwebber]

That sounds like it'll be plenty fast for us, I will give it a shot soon. Thanks for the super fast response!

[jamestwebber]

Just tried it out, very snappy. 👍

[chriddyp]

Now part of dash-core-components==0.11.0 🍻

[LucaMarconato]

@chriddyp I have tried using the dropdown in the official example here: https://dash.plotly.com/dash-core-components/dropdown with some thousands of points and the page is very slow at loading (seconds). Is your solution using a different Dash widget?