here's a small testcase that shows cpu hog in 4.5.
for bigger files, the hog is much bigger :(

$ time g++43 1.ii -c -O1 -g2
g++43 1.ii -c -O1 -g2  11,25s user 0,20s system 99% cpu 11,474 total

$ time g++44 1.ii -c -O1 -g2
g++44 1.ii -c -O1 -g2  8,53s user 0,25s system 99% cpu 8,795 total

$ time g++45 1.ii -c -O1 -g2
1.ii: In member function 'void es::ClockAnalyzer::initPrimitives()':
1.ii:38722:7: note: variable tracking size limit exceeded with -fvar-tracking-assignments, retrying without
g++45 1.ii -c -O1 -g2  34,73s user 0,45s system 99% cpu 35,237 total