When my machines were doing that on Plasma it was typically the Baloo file indexing or some Akonadi related process that was going crazy on the CPU. This week I switched back to Gnome Shell after a few years of Plasma on my main desktop and I must say it feels a lot more responsive than Plasma.
You are absolutely correct of file indexing and it was true of the prior iteration Nepomuk. It is seemingly a complex thing to get right. File indexing sucks hard in several instances
- When the OS is running on the same spinning rust or performance is substantially impacted by said rusts performance
- When the filesystem uses encryption but isn't hardware accelerated
- On first run when it has to index everything
- If the filesystem performs poorly on lots of small files.
So you boot up on a fresh install do you just not showcase features working to their fullest or do you sink performance for the first hour or hours on some systems much more than others? I think personally you ought to prompt the user to schedule the first run of the file indexing service since it will impact performance far more initially than it will thereafter.
