Speak to your MessageSpace account manager about this as soon as you can, they will offer some practical tips and ideas to implement. We started the company in 2006, and have learned a great many things along the way -- we're always happy to share our learnings and experiences.
The first thing to try is to ensure creative file sizes are kept as small as possible, which would mean they load very quickly for the user in the browser. The best performing creative file sizes tend to be under 50KB in size.
The MessageSpace audience is mostly comprised of people who are very passionate about news, politics and current affairs, and frequently return to read our sites several times in a week. For longer-term campaigns, rotating a fresh creative every week or so with eye-catching image formats will drastically improve your campaign performance.
In addition to changing your current creative/artwork, you can also test multiple creatives in the same spot by utilising our A/B testing service.