If I invoke the "Define implicit variable (in comment in current file)" quickfix for a variable in a Velocity template file, it sometimes takes more that 30 seconds to apply (I exacerbated the issue by applying the quickfix on a variable called "a").
With a longer names variable it's instantaneous.

It's like to apply the quickfix, some indexes needs to be searched and that can take a lot in some cases.

Please see the attached CPU snapshot.