Is that memory increase seen in peak usage or average/idle usage?
replyFor file servers, I could be willing to give up 350 MB of memory temporarily for large-scale indexing and thumbnailing operations if it doesn't happen often and makes the file serving/browsing more responsive.
On the other hand, plenty of NAS/file server systems are going to have paltry CPU and memory. Running slower with a more modest memory foot print might be the only way to keep the system stable.
replylibvips shouldn't be calling imagemagick for heif decode, it has a nice one built in. Unless you were using a very old libvips!
replyI've found jemalloc works best for long running libvips processes, fwiw.