Unpredictable delay before Hazel runs a rule

Does anyone else find that Hazel sometimes waits many minutes or hours before running a rule?
This is a sharp contrast to Hazel's normal behaviour, which is to run rules within just a few seconds. As far as I'm aware, Hazel doesn't crash or hang. It just waits, and sometimes seems to give up altogether.
I'm using Hazel 5.0.6 on macOS 11.2.3 on a 2015 MacBook Pro. However, I'm sure I saw a similar thing with Mojave (I didn't do Catalina), and possibly with Hazel 4, all on the same machine.
Of course I sometimes make mistakes in setting up rules (or the creators of the PDFs I'm trying to file decide to change something), but in the cases I'm talking about the rules are valid. The "Rule Status" command shows that a rule matches the file it's supposed to, and "Run Rules Now" almost always works.
This is a sharp contrast to Hazel's normal behaviour, which is to run rules within just a few seconds. As far as I'm aware, Hazel doesn't crash or hang. It just waits, and sometimes seems to give up altogether.
I'm using Hazel 5.0.6 on macOS 11.2.3 on a 2015 MacBook Pro. However, I'm sure I saw a similar thing with Mojave (I didn't do Catalina), and possibly with Hazel 4, all on the same machine.
Of course I sometimes make mistakes in setting up rules (or the creators of the PDFs I'm trying to file decide to change something), but in the cases I'm talking about the rules are valid. The "Rule Status" command shows that a rule matches the file it's supposed to, and "Run Rules Now" almost always works.