[Evolution] Evolution unresponsive using 'autocomplete', triggers re-download of WebDAV address book

[Michael Wenyon <michael wengam com>]

Autocomplete of addresses during message composition in Evolution is
generally slow for me, and in common usage can freeze, and/or stop
working, and can cause my WebDAV address book to re-download the
complete book from the WebDAV server. Re-download of my 2,700 entries
takes time (10 minutes+), during which autocomplete does not work (makes
no suggestions).

Autocomplete often works for the first entry, if I type the first few
characters of the name correctly. Problems occur when I try and edit the
characters I have typed, for example even deleting the last character
entered. Then the cursor stops flashing and the program becomes
unresponsive for a minute or more. When it comes back, I can
occasionally edit my typed characters and sometimes generate a new
autocomplete suggestion. More often, no suggestion appears, and when I
change to Contacts mode, I discover that Evolution now has no entries in
the WebDAV address book and has begun to download it again from the
server from scratch, a time-consuming process. 

Another problem seems to occur if Evolution returns many suggestions
(too many?) because the first few characters match many entries.

Generally I seem to have difficulties with adding second entry: I get no
suggestion then discover that the WebDAV is downloading again.

Evolution 3.12.1
Operating system Debian jessie/sid
Kernel Linux 3.13-1-686-pae (i686)
Gnome 3.8.4
WebDAV: OwnCloud server v 6.0.3 running on shared server (Dreamhost)
Computer: Intel NUC DN2820FYKH with Celeron processor 2.13 GHZ and 4GB
RAM, with 1 TB Toshiba hybrid HD/SSD.

My WebDAV Address Book contains 2,700 entries. It was set up manually
within Evolution, I marked it as default, marked it for autocomplete and
marked it for copying the book content locally for offline operation.
The connection with my OwnCloud server is a secure https connection.

The Personal Address Book ('On This Computer') contains a single entry
and is not marked for autocomplete use.