# Efficient evaluation of real/imaginary parts of long expressions

I have the following, rather compact, but complex, expression (see below). I simply want the real part of this. Now, when I do the usual, i.e., ComplexExpand[Re[...]]//Simplify , since all parameters and functions are real, the number of terms produced by ComplexExpand is, apparently, too large (about 6000 terms) for Simplify to handle. It has been running for almost an hour now, without any sign of it concluding with an answer.

From similar expressions in the same context I know that the result of the simplification is rather compact as well (just like the expression I start with), so I am wondering whether there is a way to skip the "Expand" part of ComplexExpand? Why expand into thousands of terms, when it then all re-collapses into a compact expression?

There got to be a more efficient way, no?

-((I E^(I m ϕ + t ωi -
I t ωr) ((1/(
1 + (iν -
I rν)^2 χ^2 Cos[θ]^2))(r^2 + χ^2 Cos[\
θ]^2) (-1 + (2 r)/(
r^2 + χ^2 Cos[θ]^2)) (-m χ (r (-2 +
r (I iν +
rν)^2 ((-2 + r) r + χ^2)) + (I iν +
rν)^2 χ^2 (r^2 + χ^2) Cos[θ]^2) \
(I RaI[r] + RaR[r]) (I SaI[θ] +
SaR[θ]) + (I ωi + ωr) (-r (r^3 + (2 \
+ r + r^3 (iν - I rν)^2 +
2 r^2 (I iν + rν)^2) χ^2 +
r (iν - I rν)^2 χ^4) + χ^2 (r (2 -
r + 2 r^2 (I iν + rν)^2) + (-1 +
r^2 (I iν + rν)^2) χ^2 + (I iν +
rν)^2 χ^4) Cos[θ]^2) (I RaI[r] +
RaR[r]) (I SaI[θ] + SaR[θ]) +
r (I iν +
rν) ((-2 +
r) r + χ^2) (r^2 + χ^2) (-1 + (I iν +
rν)^2 χ^2 Cos[θ]^2) (I SaI[θ] +
SaR[θ]) (I Derivative[1][RaI][r] +
Derivative[1][RaR][r]) - (I iν + rν) (1 +
r^2 (I iν + rν)^2) χ^2 ((-2 +
r) r + χ^2) Cos[θ] (I RaI[r] +
RaR[r]) Sin[θ] (I Derivative[1][SaI][θ] +
Derivative[1][SaR][θ])) + (
1/(-1 + (I iν + rν)^2 χ^2 Cos[θ]^2))
2 r χ Sin[θ]^2 (1/
2 r (I iν +
rν) χ ((-2 + r) r + χ^2) (-2 + (I iν +
rν)^2 χ^2 + (I iν +
rν)^2 χ^2 Cos[2 θ]) (I SaI[θ] +
SaR[θ]) (I Derivative[1][RaI][r] +
Derivative[1][RaR][r]) - (I RaI[r] +
RaR[r]) ((-r χ (-2 +
r (I iν +
rν)^2 ((-2 +
r) r + χ^2)) (I ωi + ωr) +
m χ^2 (1 + (I iν +
rν)^2 χ^2) Cot[θ]^2 - (I iν +
rν)^2 χ^3 Cos[θ]^2 ((r^2 + \
χ^2) (I ωi + ωr) + m χ Cot[θ]^2) +
m r (-2 + r + 2 r^2 (iν - I rν)^2 +
r^3 (I iν + rν)^2 +
r (I iν +
rν)^2 χ^2) Csc[θ]^2) (I SaI[\
θ] + SaR[θ]) + (I iν + rν) (1 +
r^2 (I iν + rν)^2) χ ((-2 +
r) r + χ^2) Cot[θ] (I Derivative[1][
SaI][θ] +
Derivative[1][SaR][θ])))))/((1 +
r^2 (I iν + rν)^2) ((-2 +
r) r + χ^2) (r^2 + χ^2 Cos[θ]^2)^2))