Disk space requirements more than double on upgrading to 3.4.0

Upgrading to release 3.4.0 has resulted in a large increase in disk space requirements. One installation was 67MB at release 3.3.9 and now it is 141MB, an increase of 74MB (and I am running 9 copies). Is this necessary? I cannot use the new feature as I am not running php release 7.

@Cornwell Please see this question by @skipper : New 'base' directoy mandatory?