2048-bit DH modulus provides 100-bits of security

According to the table in section 5 of https://tools.ietf.org/html/rfc3766 a 2048-bit safe prime provides over 100 bits of security.  On my laptop, a 2048-bit safe prime takes about 2 minutes to generate, but a 4096-bit safe prime takes tens of minutes to generate and is still going.