Well not anymore… I spent a little time to add new labels, and move stuff around. Who did not find an umbrella, was sent to archive. Now everything is fast. After doing that I realised that what was probably making my gmail interface slow were the “Multiple inboxes” on top. (You may activate them under settings). When opening the inbox, the “Multiple inboxes” boxes are doing a search based on the criteria in the definition. Anyway, they are still searching in the archive, but now my mailbox is responsive like before…

email has to go console. Linux powerfull tools are needed to process them faster, to find old emails etc. So far I started to use intensivelly the following tools:

• mbsync (will have a look also at offlineimap as alternative) for synchronising imap with maildir

• mutt for reading email. I tried pine earlier, but mutt is much much better

• mairix, mu,

• tagging??? since I learned the tagging of gmail, I find it very powerfull. I wish mutt would implement that. Unfortunatelly, gmail imap does not seem to share the tagging information on the imap interface. Maybe one day they will add the X-Label tag to the emails. Mutt can process the X-Label see this article.  So far I found people with similar problems/wishes:
  link1, link2
• listing of tools for maildir: http://www.qmail.org/top.html#maildir

• other tools, I will for sure have a look: http://www.nongnu.org/nmh/

• this link contains an overview of available mail tools for linux

In the isync-1.0.4/src/drv_maildir.c file, around line 368 there is a flock followed by fcntl call. It seems that the second call is blocking if the maildir is on a NFS mounted folder.

I undefined the LEGACY_FLOCK macro, so now there is call anly to fcntl. This should do correct locking on modern linux kernels. There is no deadlock now, however did not test concurrent access.