If Console is streaming log messages, typing a URL in Safari's location field will often lag before showing results. This is due to the UnifiedFieldCompletionListGenerator class sending thousands of logging messages via os_log_info().
To fix this, create a plist with the following content:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">