this server need mod_php as it was before reinstall from Centos 6 to Centos 7.
Another identical server with identical configuration, installed in same time, but with PHP 5.6 works normal:
apache/php rebuild did not solve problem.
You can't really compare these 2 memory usages. PHP 5.x allocates memory on request, while PHP 7.x allocates a large chunk of memory when it starts. This benefits PHP 7.x's performance because it doesn't need to allocate mem every time your program needs it. On the other hand, it increases mom consumption for 'small' scripts. The VIRT column with the 3,7G (if I'm correct) represents the max memory this process can address. (RAM, mapped disk memoryfiles, memory shared with other processes, etc). The SHR column shows how much memory is actually used.
Try comparing pmap <PID> and see if something looks very different (high mem usage). The mem is used by modules and/or memory these modules use. Try reducing maxrequestsperchild to lower the effects of memory leaks. But to get an apache process at 3,7g you'll have to run pretty bad php code or push a lot of modules in there... Switch tot php-fpm to find out if the cause is modules or bad php coding. Also, compare php -i outputs to make sure you have the exact same setup.