[Nepomuk] Performance issues in KDE 4.8.1

[Ignacio Serantes]

Hi,

Just installed KDE 4.8.1 I found a severe performance issue with my
plasmoid Drop2TagIcon.

Some investigation reveals that the problem is the call to
Nepomuk.Tag.allTags() and, as I have 5 Drop2TagIcon in each of my four
activities, the final result is that Plasma was totally frozen.

Sadly this seems not restricted to Python, in irc Jörg Ehrichs has similar
issues with Conquirere and a few minutes ago, when I'm trying to tag files
using Dolphin in the old fashion way, I discover that the problem is here
too.

More information:
- I have only 144 tags.
- Over 7-8 seconds passed between I click in Dolphin "Add Tags..." and the
dialog is displayed.
- Meanwhile over 33% of my dual core CPU is used by the nepomukservicestub
that launches virtuoso.
- The next query:

SELECT ?uri ?label

WHERE {

?uri rdf:type nao:Tag .

OPTIONAL { ?uri nao:prefLabel ?label . } .

} ORDER BY ?label

took over 150-170 milliseconds using NepSak and consuming 6% for an instant.

-- 
Best wishes,
Ignacio
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