Hot reloading takes a lot of time

[SaadBazaz]

When developing using this library, hot reloads take a lot of time.

This occurs not only in the demo in this repo, but also happens in external projects using this library as an installed package.

I have a hunch it's because of Lit, or because of getSlotProp.

[SaadBazaz]

Possible reason?
lit/lit#1844

[SaadBazaz]

We're using this library in a professional project.

It's done well for us so far, but the biggest problem (out of many) is that hot-reloading in NextJS stops working when we use our library. Also, consequently I think, builds take too long.

We are considering revamping all our project's interface due to this. It's a huge issue.

If someone could fix this for us, that'd be awesome.

Hint:
I feel like it's got something to do with our usage of shadow DOMs. Maybe if we don't use Shadow DOMs, it might bring back this functionality (along with many others).

We've set up a bounty of 17.5 USD (negotiable) if someone from the community takes it up and delivers.

[msaadg]

Okay, so I tried reproducing the issue and have noticed two things. The hot reload does not seem to work when I do pnpm dev and the application compiles and starts for the first time. However, when I refresh it once, the hot reload seems to start working but it takes too much time.

When I refresh the following logs are outputted, I feel this might be very relevant:
index:dev: 'CustomElementRegistry' already has "md-badge" defined. This may have been caused by live reload or hot module replacement in which case it can be safely ignored. index:dev: Make sure to test your application with a production build as repeat registrations will throw in production. index:dev: 'CustomElementRegistry' already has "md-elevation" defined. This may have been caused by live reload or hot module replacement in which case it can be safely ignored. index:dev: Make sure to test your application with a production build as repeat registrations will throw in production. ......

Multiple versions of Lit are also loaded which might explain why it takes so long to hot reload.

reproduce_hot_reload_comp.mov