Bug 1701660 improves CSV performance by fixing UI refresh. This bug will address performance penalty added by CSV reading/parsing/processing.

Here are some performance numbers for me on a M1 MacBookPro for importing from a csv file:

500 rows - 234 milliseconds
2500 rows - 1.4 seconds
10000 rows - 10 seconds
58000 rows - 7.5 minutes

The time to add a login is exponential, I assume because each new login is compared to previous ones. If I disable the duplication comparison, the numbers go down significantly, 10000 rows takes 5 seconds and 58000 rows takes less than 2 minutes.

Note that the browser is unresponsive during the import in all cases.

Hey Neil,

Are you working on this? We've added password CSV / TSV import to the new migration wizard, and that also uses ImportFromCSV, and our current plan is to have this ride out in 114.

We discussed this and don't think this is a high priority. Telemetry shows that almost all users have no more than 500 passwords which wouldn't take long to import. The ultimate goal would be to show a progress meter or somesuch in the summary that would update, possibly just doing this in batches instead.

Lets close this bug since we aren't planning to work on it. When we have more reasons to improve performance, we will open a new one or reopen this one.