Excessive Rendering Lag Makes WebUI Unusable With Default Settings

[tayl]

qBittorrent & operating system versions

Firefox 131.0.3 (64-bit)

Qt: | 6.7.3 Libtorrent: | 1.2.19.0 Boost: | 1.86.0 OpenSSL: | 3.3.2 zlib: | 1.3.1.zlib-ng

What is the problem?

Moving this by request @glassez: https://github.com/qbittorrent/qBittorrent/issues/21595#issuecomment-2424482111

Just to add another data point, I'm experiencing extreme lag in the web UI with default theme running on Linux. It may be totally unrelated, but maybe not - the root cause may be the same. With 500 or so torrents, each call to /api/v2/sync/maindata is returning about 1 million characters, or about the same number of bytes / 1MB. Compressed that's about 132kB over the line. This payload is returned regardless of what the UI is showing - i.e. if I'm filtered to one torrent, I still get the entire payload. Maybe that's a reasonable design choice, I don't know the underlying system well enough to say. But I don't think that's the primary issue.

When all my torrents are showing, each time this data is parsed, there's a period of about 1 second that the UI takes to "redraw" the 1MB payload (notably, UI is blocked during this time). 90% of this time is spent in dynamicTable.js#updateRow. When I filter down to a single torrent, the time taken to "redraw" is unnoticeable. Confirmed that prior to 5.0.0, this issue did not exist.

A refresh rate of 1 second in advanced settings makes the web UI basically unusable. I have it set to 5 seconds now and it's okay but not a real fix.

Firefox 131.0.3 (64-bit)

Qt: | 6.7.3 Libtorrent: | 1.2.19.0 Boost: | 1.86.0 OpenSSL: | 3.3.2 zlib: | 1.3.1.zlib-ng

Steps to reproduce

No response

Additional context

No response

Log(s) & preferences file(s)

Default settings