What does autojoin do? Using the 'autojoin' optimization can increase performance on fields that get used a lot. Not using it can reduce the page's memory footprint. What is more desirable in each instance depends on your situation. What sites should use autojoin? Autojoin is most applicable with larger sites. On smaller sites, there may be no benefit to using it or not using it. But it's good to know what it's for regardless. Where do you control autojoin? Autojoin is contr