Many bloggers keep complaining that their blogs were suspended by web hosting companies because of heavy server usage and they plan to change the CMS thinking there would be problems in the CMS but the main problem is in the plugins which are you running.
The best suggestion for high traffic blogs with high amount of images and blogs which have a lot of plugins enabled is to use a wordpress plugin named : WP Super Cache which can help you in decreasing your server load by reducing the sql queries processing by creating html files. When it is installed, html files are generated and they are served without ever invoking a single line of PHP. This plugin works perfectly even though your website has hit homepage of Digg or slashdot generally called as the Slashdot effect and handles any type of traffic loads by enhancing the performance and helping the server from getting crashed.
You can download the Super cache plugin here