Comment 18 for bug 42199

gpg spawns a background process to update the trustdb at some very regular time. I suspect this may be what's going on. I noticed this when using gpg through mutt in that mutt would wait a very long time once in a while. I wonder if evolution is killing it? Robert, does adding this to your .gnupg/options file make it go away?

no-auto-check-trustdb

With this option, you need to run the trust checker once in a while, or gpg gets mad. I run this once a day from cron:

37 5 * * * gpg --check-trustdb 2>&1 | egrep -v '(depth: | needed,|next trustdb check)'