Query takes 19 secs - how to speed it up?

[WolfgangFahl]

https://qlever.cs.uni-freiburg.de/wikidata/qwZEdr takes 19 secs and times out on wikidata query service

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
            PREFIX wdt: <http://www.wikidata.org/prop/direct/>
            PREFIX wd: <http://www.wikidata.org/entity/>
            SELECT ?item ?itemLabel
            WHERE {
              {
                ?item wdt:P31 wd:Q101352.
                ?item rdfs:label ?itemLabel.
                # short name
                ?item wdt:P1813 "Abbas"@en
                FILTER(LANG(?itemLabel)= "en" )
              } UNION {
                ?item wdt:P31 wd:Q101352.
                ?item rdfs:label ?itemLabel.
                FILTER(?itemLabel= "Abbas"@en )
              }
            }

[WolfgangFahl]

https://qlever.cs.uni-freiburg.de/wikidata/TXa49v takes 1 msec (on second call)
https://qlever.cs.uni-freiburg.de/wikidata/Hfp0wh takes 1.3 secs on first call and 1 msec on second call

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX wd: <http://www.wikidata.org/entity/>
SELECT DISTINCT ?item ?itemLabel
WHERE {
  ?item wdt:P31 wd:Q101352.
  ?item rdfs:label ?itemLabel.
  FILTER(LANG(?itemLabel)="en").
  FILTER(?itemLabel= "Abbas"@en )
}

still problematic on WQDS

[joka921]

The solution for your initial question would be:
Try adding the language filter also to the second half of the UNION (it is semantically clear via the FILTER, but QLever is not (yet?) smart enough for this:

see here
(about 1.5 seconds on a cold cache).

For the WDQS, you can speed it up via the following hack
try me, but this does not work for arbitrary queries.