Boonex recently posted a blog at Unity regarding speed improvements for Dolphin. Most of it seems to be hosting related, or more specifically a mysql configuration change.
They suggest adjusting the my.cnf file. If you have some form of shared hosting this will not be possible for you to change. Your hosting provider can do it, but since it affects the entire server I doubt most will be willing to do this to satisfy one customer. You can ask them and point them to the Boonex post about this, but don't count on your host doing so.
If you have a vps or dedicated server with root access you will be able to do this if you know what you are doing. Follow the information Boonex suggests in this post:
Hosting Server Setup Recommendations for Optimal Dolphin 7 Performance
You really should run some kind of test with your current configuration before and after applying the changes to really know if it helps. You need something to compare the before and after, otherwise there is no way of knowing for sure if it has helped in any way.
In addition to the mysql configuration Boonex goes on to compare the following setups:
They provide a brief description of each along with their opinions of the Advantages and Disadvantages of each.
mod_php (dso module) used to be the most common setup. It is still very popular, and easier to set up. Many hosts have been switching to suPHP or FastCGI for increased security recently.
The part I don't understand in their post about mod_php (dso) is they say "security" is an Advantage. Then, right after that they state "maybe insecure on shared hosting".
I guess they mean it would be a little more secure if it were all your server like vps or dedicated. Otherwise, if it's a shared server with many other accounts then not so secure.
I would still be concerned if using mod_php (dso) when it comes to security even if it was a vps or dedicated server with only my accounts on it.
You can also find Advantages and Disadvantages of the other types if interested there in the Boonex post too.
SuPHP is obviously the slowest. FastCGI with eAccelerator appears to be the fastest setup not only for Dolphin, but probably for most web hosting in general. It can be a very secure environment if it is setup correctly. However, it is somewhat more complicated to configure than the other types mentioned above.
I personally try to avoid mod_php (dso module) hosting as much as possible. Although it can be fairly fast, it lacks security in my opinion.
suPHP is a bit slower. It might depend on how much activity, how many other sites, and accounts are on a server. I would take suPHP over mod_php (dso module) any day if I had the choice.
Ideally FastCGI / FastCGI with eAccelerator would be my first choice. Providing it was actually setup and configured properly for speed and security.
A lot of hosts have been switching from mod_php (dso) to suPHP recently. Some have even switched to FastCGI.
If you are looking for dolphin hosting it might be a good question for the company you are thinking about going with.
In addition to any other questions you have for a potential hosting company you might ask them something like:
Which of the following are your servers configured and setup with?
Hosting is just one of those things that are almost never totally perfect. There are so many different ways to set up and configure a server. Some hosts pack in a lot of accounts per server. That's how they make their money. So you really never know what kind of performance you will see until you try. Another thing that can happen is the server seems fast for a while. If it is a brand new server and there are only a few other accounts on it so far it will seem very fast. As more people purchase hosting and get put on the same server it can start to slow down quite a bit over time.
Another thing is that even if you find a host with the fastest FastCGI with eAccelerator setup, it won't be that fast if they overload the server with too many other accounts.
That is one thing the post by Boonex doesn't really take into consideration. They are just comparing the same or similar setup and site.
So if your host seems to overload the server with too many other accounts it might be time to look for new dolphin hosting.
The only way to have the most control is a dedicated server, which can be out of most people's budget.
Vps is a cheaper option with a bit more control, but you really don't know how many other vps accounts are on a server either. Whether a host may overload them too or not.
Good luck to those that have root access and are going to test it out. I hope it works out for you.