ACU Slowness with W Server 2012

When our customer migrate our application Acu 32 bit from W2008 to W2012, they note extreme slowness. 

They  report us: "if we try to use a single processor instead of one multiple performance improves".

This occurs with all 32-bit runtime (8.1.2, 9.0.1, 9.1.0, 9.2.1, 9.2.4)

Has anyone had these problems?