Quit[]

<<FeynCalc`;

bb=k;
ScalarProduct[bb,p1]=0;ScalarProduct[bb,bb]=0;
ScalarProduct[p1,p1]=m^2;ScalarProduct[p2,p2]=m^2;
ScalarProduct[p1,r]=0;ScalarProduct[bb,r]=0;
ScalarProduct[bb,p2]=0;ScalarProduct[r,p2]=1;
ScalarProduct[p1,p2]=0;

amp=SPD[r,z] SPD[bb,z] SPD[p2,z] SPD[p1,z] FAD[{z,0},{p1+bb-z,m},{p2-z,m},{p1-z,m}];

TID[amp,z]//ExpandScalarProduct//Simplify//AbsoluteTiming

ExpandScalarProduct[SP[-p1+p2]]
ExpandScalarProduct[SP[-p1+p2-k]]

TID[amp,z,SPC->False]//Simplify//AbsoluteTiming

TID[amp,z,SPC->False,ExpandScalarProduct->False]//Simplify//AbsoluteTiming

%[[2]]//ExpandScalarProduct

OneLoopSimplify[amp,z]