I just ran two parallel bootstraps of mainline and 4.0, on a single-processor Athlon XP 2600+.
Configuration was with --prefix=$HOME --enable-languages=c,f95 in both cases. The 4.0 build, which finished earlier, used real 58m0.437s user 25m1.021s sys 1m36.735s The 4.1 build used real 67m24.663s user 38m19.830s sys 1m41.125s The compiler used for boostrapping was $ gcc -v Using built-in specs. Target: i686-pc-linux-gnu Configured with: ../gcc-4.1/configure --prefix=/home/ig25 --enable-languages=c,f95 Thread model: posix gcc version 4.1.0 20050402 (experimental) $ cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 6 model : 8 model name : AMD Athlon(TM) XP 2600+ stepping : 1 cpu MHz : 2083.203 cache size : 256 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmovpat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow bogomips : 4128.76 -- Summary: [4.1 Regression] Bootstrapping 4.1 takes 50% longer than 4.0 Product: gcc Version: 4.1.0 Status: UNCONFIRMED Severity: normal Priority: P2 Component: bootstrap AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: Thomas dot Koenig at online dot de CC: gcc-bugs at gcc dot gnu dot org GCC host triplet: i686-pc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20783