PHP echo or plain html
When html and php code mixing is required in php development, at that time writing html code as it is is faster than printing html code using echo or print function. Reason is PHP interprets and compiles each php code statement and ignore any thing writting outside php tag. Hence php echo for html is slower compared to direct writing php.
Question is how to separate php and html for readability in php development. Better solution is write down html code in separate file and include that file in php. This way readability will increase while PHP web development and also speed will be achived.