if you have multiple cores, for example 8 cores, load 8 is normal. in this case, load 1.3 still low.
so far by your tests, 4.2.12 + Process Group load is higher than 4.2.12 + Suexec Daemon, 1.3 vs 0.3, about 4 times higher.
need more load tests, is it always 4 times ? for example when suEXEC...