I keep reading that particleshop crashes Affinity Photo. Went to the plugins list, and yes athentech's perfectly clear is listed, but so is particleshop.
I'm running a laptop with 4 gigs memory, an AMD A8 processor, and Win 10. It works as well with Affinity as it did with Corel's Paintshop Pro 2018. Bought Affinity after Corel started playing games with their licensing, and was hoping I could keep the plugins that were bundled with versions 6 - 2018. Some work, some don't.
I had already used it on my desktop (8 gigs memory, AMD 4 core processor, Win 10) with the same results as above.
You may want to recheck particleshop's compatibility with Affinity.