ksh shell hangs if setting variable from command that produces more than 120k

Issue

On ksh-20120801-10.el6_5.3 there is a problem that following command will not come back with a result for at least 1 hour

$ FILES=`find /usr/include -type f`

• where find brings a huge amount of files

$ find /usr/include -type f |wc -l
10002