LP:941889 - JOIN constructors takes a long time in 5.3

I run sysbench on MariaDB on Windows with Visual Studio sampling profiler , comparing 5.2 and 5.3 performance.
sysbench version is 0.5 and for the test I created select1.lua, which does nothing else but running prepared "SELECT 1".

Performance reports show a big difference inside JOIN constructor, and for this specific test JOIN::JOIN is the most expensive function with 24.23% exclusive samples.

Here is he list of functions that show up as more expensive in 5.3 compared to 5.2

Comparison Column Delta Baseline Value Comparison Value
JOIN::JOIN 23,15 1,08 24,23
RtlpAllocateHeap 3,24 0,00 3,24
RtlpInsertFreeBlock 1,93 0,00 1,93
RtlpFreeHeap 1,42 0,00 1,42

Looking at what has changed from 5.2 to 5.3, JOIN structure grew from around 5K to around 32K. Besides, it contains 2 large arrays of POSITION structures, and POSITION has a non-trivial constructor, since it includes semi-join strategy classes for which virtual function tables must be setup (confirmed by switching to disassembly and single-stepping through JOIN::JOIN)