My window freezes whenever i try to run a loop which has even 100000 iterations which are quite less for a computational device.

Let say i run :

[| temp |

temp := String new.

(1 to: 100000)

do: [:i | temp := temp, i asString, ' ']] timeToRun.
The time taken to compute is a few milliseconds , but the program freezes for quite a few seconds, What can be the problem ?