Loop_start slows blog down

Hello,

Since I updated my blog to version 2,7 the pages load very slow. The header shows up imedietly, but then i have to wait for 5 – 10 seconds before my post shows. I take’s this time for each post on the page.

I already contacted my hosting provider. They say that nothing is wrong.

Now i downloaded the plugin ‘wp tuner’ to look what might slow down the site. I says there are two slow part;
the first is the sidebar. Why this is, I dont know, might be the theme i’m using.

The second problem that slows down the site, according to wp-tuner is something called ‘loop_start’.
Can somebody tell me what this is, why it could slow down the site en how i can be fixed.

Thanks,

Jarno