server load and specs

I installed suitecrm on a server on a cloud (remote hosting) for my organization. I have about 30 -50 people connected to it and only the administrator performing a lot of usege in it (uploading leads managing users etc) but the load on the server is very high (can get to 90 percent of the cpu). someone knows how many users can use the crm on a standart server? or share recommended server specs for about 60 users?