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[BUG] dcc.Dropdown in dash 4.0.0 is considerably slower than before #3616
Description
I have a dash app with dcc.Dropdown with thousands of options (around 8000). In dash 3.4.0 the dropdown works amazingly (e.g. beating dmc.Select by a margin in speed). In dash 4.0.0, the performance degraded considerably.
Here is a minimal app to simulate the issue:
import random
import string
import dash
# Generate 8000 random options
def random_string(length=8):
return ''.join(random.choices(string.ascii_letters + string.digits, k=length))
options_list = [
{"label": f"Option {i} - {random_string()}", "value": f"value_{i}"}
for i in range(8000)
]
app = dash.Dash(__name__)
app.layout = dash.dcc.Dropdown(
id="my-dropdown",
options=options_list,
placeholder="Select an option",
searchable=True
)
if __name__ == "__main__":
app.run(debug=True, host="127.0.0.1", port="8050")
For the two versions, try typing "78" to obtain filtered options and then deleting the search string to obtain the full list of options and compare the timing.
I understand that this many options may be stretching the limits a bit (and I know it would be better to only show a subset in most cases). Nevertheless, it would be nice to keep the previously achieved performance :-)
Finally, let me appreciate the new styling (of the dropdown) in dash 4.0.0!
Reacted by Colin Geukes
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BSd3v commentedon Feb 21, 2026
I'm wondering if it's related to the use of memo here:
https://github.com/plotly/dash/blob/dev/components/dash-core-components/src/fragments/Dropdown.tsx#L59-L67
ColinGeukes commentedon Mar 9, 2026
I am experiencing the same issue, the load takes too long, without any indication something is happening in the background
ggydush commentedon May 4, 2026
+1, also seeing this issue persisting on 4.1. I have 70k options that performs great on 3.4, but lags considerably on 4.1.0
dudechem-rf commentedon May 7, 2026
+1, also still seeing this issue in 4.1.0. With version 3.3.0 it performed very fast. I currently have 4000 options, each option is a string with ~200 chars.
I ran some tests:
With 1000 options it is already very laggy.
random 5 char strings per option and 4000 options --> very fast