Performance

Is it true that mixing HTML and PHP--switching back and forth with <?php ?> tags--slows down performance? (I'm using PHP4.) Is it better to echo output than to drop out of PHP mode? And concerning database connections, my ISP asks that I always close a MySQL connection with a mysql_close()--which I can understand. But I'm curious, if I have to make, say, 10 SELECTs throughout a page (in the header, body, and footer), is it perhaps faster to use the mysql_close() at the very end of the page (in the bottom of the footer.inc)? In other words, is there any disadvantage performance-wise (or stability reason) to open and immediately thereafter close mysql connections? Can anyone recommend an article or two on coding techniques for improving PHP and MySQL performance? I don't wan to spend the rest of my life optimizing my php code, but if I knew a few basic rules about its performance characteristics, I might be able to make better decisions when coding. Thanks. ...Rene --- René Fournier, rene.fournier@markada.com