Hello Im implementing Citrix with FSLogix in a client where they have several mailboxes and use PST files. What would be the best way to deal with this, performance wise?

Either store the PST files on a network share, or don't use them. Because the PST files can blow up your FSLogix storage quickly.

Yup, thats my worry, it blowing up the FSLogix profile and boom, horrible performance. Network share isnt recommended by MS. The FSLogix Office profiles? How is that?

You only use the Office profile if you are using a different profile solution, they don't recommend doing Office profile on top of a full container.

So FSLogix and FSLogix Office are not recommended?

Correct.

If a new deployment you may want to rethink going with FSLogix. Microsoft’s direction is for fslogix to skew more to their offerings such as AVD and less to partners like Citrix.

But UPM really has the same limitations. PST will blow up their containerization. Also MS has backtracked some of that PST on network locations.

Use Office Container only if a) you are managing the profile through another technology and want containers for Office, or b) you want to be able to delete and reset the Office cache without digging in to the whole container, or c) you want to keep the Office cache on a different storage tier to the profile containers, or d) you are replicating the containers and don't want to waste storage/time on replicating the Office cache

It's a Citrix deployment (if you are insinuating something different, not to go with Citrix)

I'm talking in general

UPM symlink with pst spread across multiple storage would do a good job.

I would step away from PST files in general. They always make the end user experience worse in terms of performance. Just import them into the mailbox, you can use archiving on your O365 / exchange plans, use FSLogix profiles and configure Outlook with GPOs to only download the last 3 months, so your FSLogix profile doesn't explode

The ideal path would be to move them to exchange but like I said: Each one would need a 365 mailbox and license