burger's questions

I am running apache2 (2.2) on Ubuntu on a VPS with 768MB of RAM. For some reason it takes several seconds to load any page (even static html). The only component I can blame is Apache. However, I have no idea why it is acting that way. I even installed NewRelic to see if maybe it would help me diagnose the problem in a more visual and friendly format. I see that apache2 is using about 400MB of RAM, which seems like a lot, but the total is still well under 100%. I am still confused as to what the real problem is or how to properly diagnose it.

Memory usage according to top (as asked by answerer):

Mem:    768848k total,   753380k used,    15468k free,    39792k buffers
Swap:   262140k total,    92696k used,   169444k free,   432888k cached

Results for "free -m":

             total       used       free     shared    buffers     cached
Mem:           750        733         17          0         35        414
-/+ buffers/cache:        282        467
Swap:          255         90        165

I am running a single MongoDB database. No sharding. When I run htop, I see a lot of instances of mongod. Is that normal? Does every connection create a separate mongod process? Should I be concerned?

For some reason when I use top, only one of them is shown. That part is confusing also.

As asked in the comments, output of "ps axjf | grep mongod":

12858 12878 12877 12858 pts/0    12877 S+     500   0:00              \_ grep mongod
1  2691  2690  2690 ?           -1 Sl     497  70:54 /usr/bin/mongod -f /etc/mongod.conf

I apologize if this question is rather basic, but it is seems to be too broad to easily find a solution. I am running apache2 on Ubuntu on a VPS with 768MB of RAM. I am also running MySQL on the same machine. However, as my database grew in size, I ran into performance issues. I decided to try MongoDB. MongoDB is hosted on a separate server, so it should not affect anything on the web server. After I moved one of the tables to MongoDB, I did notice an improvement in performance. Last night, I converted more tables to MongoDB. Everything was working fine. However, this morning, the website was not reachable. Restarting apache solved the problem, but within 30 minutes I could not reach the site again.

I checked the apache error log and there was nothing suspicious there. What else should I look at?

Also, I don't even understand why this would be happening. Since I am moving some stuff off the server, there should be fewer issues, not more.