My computer is Mac Pro M1, 2020.

General Comments: for expand, SymEngine is nearly as good as Mathematica, Symbolics‘s “expand” function still needs to be greatly improved. substitute are similar for the three CAS in performance.

- expand,

Symbolics (code+time)

```
f=(x+big(2)y)^6000|>expand; # 64.2s
f=(x+big(2)y)^100000|>expand; # looks infinity
```

SymEngine

```
f=(x+2y)^6000|>expand; #0.5s
f=(x+2y)^100000|>expand; # 10.6s
```

Mathematica takes 0.01s and 3.1s respectively.

- substitute

Symbolics takes 0.9s

```
substitute(f,Dict(x=>big(1),y=>big(2)));
```

SymEngine takes 0.4s

```
subs(f,Dict(x=>1,y=>2));
```

Mathematica takes 0.06s