Hello,
Does this happen even when adding new highlight for a new page?
Or only when adding new highlight for existing page that already have many other words to highlight?

In general, the highlighting is slower when you have:
- many words to highlight on a single page
- if you are using regular expressions (RegExp)
- if the page where it runs is complex/huge, with a lot of elements (like Facebook / Reddit)

I plan to look into some performance optimization in the new release (in a few weeks).

You can also contact me here:
admin@fastaddons.com

Best Regards,
Juraj Mäsiar

Hello,
Currently no, only by using RegExp option and separating search phrases with pipe symbol "|" instead of comma ",".
So you would have "word1 word2|word3".
However, you will have have to escape the special RegExp symbols.
I'll try to improve this in the upcoming release.
Best Regards,
Juraj Mäsiar

Hello Alex,
Great idea!
I'll put it on my todo list for the upcoming release.
Note however that I'm not sure when will I start to work on the new release.
There is many features planned for this release and my free time is quite limited now.
I'll see what I can do...
Best Regards,
Juraj Mäsiar

Hello,
Thank you for the feedback and specific example!
I do plan to add groups support for some time, but every time I start planning the architecture, I get stuck with some huge obstacle that requires a huge redesign (not just visual but also data storage and synchronization).
Also, I'm currently super busy with my other addons, so this one will have to wait a bit.
I'll see what I can do when I get back to this one.
Best Regards,
Juraj Mäsiar

Hello,
Sadly, this is a browser limit and they don't want to increase it:
https://github.com/w3c/webextensions/issues/510
I plan to implement custom synchronization, but that will take some time.
Note that you can change the storage to "local" which is unlimited, but not synchronized/backed up, to other devices. See Settings / Options / Storage .
Best Regards,
Juraj Mäsiar

Hello,
The path to auto-save is not really possible, addons doesn't have direct access to drive, apart from creating a file in the default "Downloads" folder.
I plan to add some kind of remote synchronization, although I'm not sure when exactly (I've build too many addons and many of then needs upgrades :)).
Best Regards,
Juraj Mäsiar

Hello,
Sadly, browsers doesn't allow extensions to run in the PDF files anymore, more info:
https://bugzilla.mozilla.org/show_bug.cgi?id=1454760

Theoretically, it should work if you would use some online PDF viewer.
But I've just tried a few and none of them worked as expected. Seems like they use "canvas" to render the content so my extension can't access the words there.
But it does work in the Mozilla online PDF viewer demo, so it should be possible:
https://mozilla.github.io/pdf.js/web/viewer.html
I wish I had more time for experiments, but sadly I'm currently quite busy with my other extensions. I'll put it on my todo list so when I start working on a new version, I look into it.

Regarding contact to me, you can write me email here: admin@fastaddons.com

Best Regards,
Juraj Mäsiar