FilePicker.PickMultipleAsync very slow

[joshua-lemli]

Description

Using the FilePicker.PickMultipleAsync seems to be very slow. I have a process where a user selects multiple files (which will later be parsed). The method to pick the files is much slower than the code that actually reads/parses the files afterward! This shouldn't be the case.

File picker is basically unusable due to the many seconds of latency between when the dialog is closed and the results become available (i.e. when the method returns).

It seems like the file picker actually touches/reads the files after the user closes the dialog? Picking files in a location with high latency (e.g. a network drive) is much slower than picking the same files from local system.

Here you can see the time the FilePicker is busy, picking about 250 files (each ~100kb), it takes almost half a minute for the file picker to return the result!

The time between closing the picker dialog and await FilePicker.Default.PickMultipleAsync() completing seems to increase linearly the more files are selected.

Testing with VS 17.7.5 and .NET7 with an empty/boilerplate MAUI Blazor project. Building for release/debug does not appear to impact the issue. Deploying to windows, win-x64, all tests on a windows-11 machine.

Steps to Reproduce

1. Create a MAUI project (I'm using MAUI Blazor)
2. Use the default FilePicker and invoke PickMultipleAsync (awaited or not, doesn't matter)
3. Select more than a few dozen files and accept the selection in the dialog
4. Method takes an unreasonable amount of time to complete (more than several seconds)

Link to public reproduction project repository

No response

Version with bug

7.0.96

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

Windows

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output

No response

[ghost]

We've added this issue to our backlog, and we will work to address it as time and resources allow. If you have any additional information or questions about this issue, please leave a comment. For additional info about issue management, please read our Triage Process.

[mjsb212]

joshua-lemli I'm having a similar problem. How many files are you picking? Mine lags after about 200-500 files are chosen. Anyone know a workaround?

[joshua-lemli]

joshua-lemli I'm having a similar problem. How many files are you picking? Mine lags after about 200-500 files are chosen. Anyone know a workaround?

@mjsb212 I definitely notice lag picking hundreds of files, often when picking far fewer. In scenarios where the files are slow to be accessed (e.g. a network drive) the issue is compounded -- this seems unnecessary for a tool that just delivers file paths, especially when a user can already view and select those paths.

It's not much of a work-around, but, building a custom file-picker in MAUI (Blazor hybrid) is quite simple, and is the best solution I've found. This is just unfortunate given that the MAUI FilePicker exists and (technically) works. There are also UI toolkits (like Radzen) that offer their own file-pickers, although I do not know how performant they are.

[MartyIX]

This seems to be the same issue as #19868 which was fixed.