Significant slowdown of qbs project parsing

Start Qt Creator with enabled QbsProjectManager and open qtcreator.qbs from Creator's repository, v3.2.0. Wait until parsing the project finished and the project tree is being populated.

With a release build of Creator on my home machine this has been taking about 45 seconds since Creator 3.2. Now it takes about 75 seconds. Bisecting led me to the following change:

db0dc474c2bea9a108f0ae4b7575cfab395556e2 is the first bad commit
commit db0dc474c2bea9a108f0ae4b7575cfab395556e2
Author: Joerg Bornemann <joerg.bornemann@theqtcompany.com>
Date:   Thu Jan 29 14:10:14 2015 +0100

    fix look-up of scalar properties

Please check whether you can speed this up again.

Noticed in Squish test tst_opencreator_qbs.