People who read too quickly in the IELTS test often miss the answers. If you go too fast, you won't really understand what you're reading, and you'll start to panic when you don't find what you're looking for.
On the other hand, some people read too slowly; they read each word as if it were a separate item on the page. These people tend not to finish the test.
Instead of skimming too quickly or reading each word slowly, I recommend that you read phrase by phrase. For example, read the first sentence of this lesson as three phrases:
People who read too quickly ..... in the IELTS test ..... often miss the answers.
Try to get into the habit of reading phrase by phrase. You should find that you can go at a reasonable speed and that you'll understand (almost) everything.