The current counter overlay shows that it is "instant" but is actually limited by your max current belt speed. For diagnosing, that creates problems.

This was originally created as a bug (which is still an option), but Thomas specifically suggested a feature suggestion update instead as he was worried about potential confusion.

Either it should be updated (preferred) to be truly instant like a splitter, or the tooltip should be updated to the current max available speed. This has created several questions in the Discord (today most recently).

The original bug report with details is listed here: https://discord.com/channels/1248736286026764401/1472171333088444466