16 seconds is excessive, and suggests a latency problem with your server.
I just timed a cold start with this mastodon.social account and it was less than 5 seconds.
Pachli has to make a number of requests to your server before it can start showing your timeline. Some of these can run in parallel, some it has to wait for before proceeding.
Looking at a cold start with an account on mastodon.social Pachli makes the following requests (I've added the time it took for the most recent one too):
/api/v1/accounts/verify_credentials, 1,405ms
