"Custom command" has a delay that's exacerbated by simultaneous notifications

[blackwind]

There seems to be a delay of just over one second when using the "custom command" engine. When calling my command directly from the command-line, I experience no such delay.

This is particularly problematic when multiple notifications are triggered at the same time. I ran a test opening ten notifications at once, and it took over five seconds for any of them to appear.

If it matters, I'm on Windows 10 1607. No, I can't switch to Linux.

Is there anything you can do to speed up "custom command"?

[mkiol]

Thanks for the report. Are you using Firefox or Thunderbird?

[blackwind]

Running Firefox 53.