# 100 digits #
prec=100;
x=N[Sqrt[3],prec];
y=N[Sqrt[5],prec];
eps=N[1/10^10,prec];

n=100000;
1000*(Timing[Do[x*y,{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
(* modify divisor since Mma caches 1/y *)
1000*(Timing[Do[x/(y+i*eps),{i,n}]][[1]]-Timing[Do[y+i*eps,{i,n}]][[1]])/n
1000*(Timing[Do[Sqrt[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
n=10000;
1000*(Timing[Do[Exp[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
1000*(Timing[Do[Log[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n

# 1000 digits #
prec=1000;
x=N[Sqrt[3],prec];
y=N[Sqrt[5],prec];
eps=N[1/10^10,prec];

n=10000;
1000*(Timing[Do[x*y,{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
1000*(Timing[Do[x/(y+i*eps),{i,n}]][[1]]-Timing[Do[y+i*eps,{i,n}]][[1]])/n
1000*(Timing[Do[Sqrt[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
n=1000;
1000*(Timing[Do[Exp[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
1000*(Timing[Do[Log[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n

# 10000 digits #
prec=10000;
x=N[Sqrt[3],prec];
y=N[Sqrt[5],prec];
eps=N[1/10^10,prec];

n=1000;
1000*(Timing[Do[x*y,{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
1000*(Timing[Do[x/(y+i*eps),{i,n}]][[1]]-Timing[Do[y+i*eps,{i,n}]][[1]])/n
1000*(Timing[Do[Sqrt[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
n=100;
1000*(Timing[Do[Exp[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n
1000*(Timing[Do[Log[x],{n}]][[1]]-Timing[Do[,{n}]][[1]])/n