Please attach a log file.

I would like to say that this occurs with hwdec=yes, with hwdec=no or without any option.

I'm testing linux mint 20.1 cinnamon beta because i am the Linux Mint(as well as Celluloid) Portuguese(pt) translator without any changes, in live mode and i just open a .mp4 movie... although Celluloid plays the movie, clicking on the close button or anywhere else it takes too much time to react. If clicking on the close button takes a long time until Celluloid closes.

Ceeluloid_log.zip

I would like to say that this occurs with hwdec=yes, with hwdec=no or without any option.

Seems like this isn't related to hwdec then.

although Celluloid plays the movie, clicking on the close button or anywhere else it takes too much time to react

Are you using Intel iGPU? I think this might be related to the Intel iGPU performance regression that happened around Linux 5.7. On my Haswell machine, I'm also getting freezes when using more demanding options like scale=ewa_lanczos even though they worked perfectly fine with older kernels.

Yes, i'm testing in a old laptop, (Acer Extensa 5620Z), it must be because of that,