Help: Is WP Multisite the right solution here?

Hi, everyone!

I’m having a hard time making a decision, and I wanted your opinion on it. I’ve been reading a lot about WordPress Multisite lately, and I think it might be ideal for my website, but I wanted a second opinion. Here is the situation:

• I have a rather complex website, that consists of a blog (in magazine style) and some tools, such as a event calendar, an interactive map, and a directory of blogs with over 3.000 blogs.
• Each of these tools uses a plugin.
• Every time a user enters any page of my website (such as a post on the blog), all the plugins are loaded, and that is making my website very slow. There is no need for all the plugins to be loaded, as each one is used ONLY on it’s own section (for example, the calendar plugin is only used on the calendar page, and so on).

My idea is to switch to WP Multisite, and keep the blog as the main site, and then create subdomains using WP Multisite such as map.mysite.com, calendar.mysite.com and so on. In this way, I could install the plugins only on the sites they are used, and loading would be faster. Also, I would be able to better configure templates/themes for each section of the site.

Is this a good idea? Is there any “bad side” to this I’m not seeing? For instance, could this hurt my SEO or make my site even slower?

Waiting to hear what you think!