Regarding optimize magento 2 website

[yagniksphp]

According to Magento 2 functionality for better performance,  I changed mode default to production after complete my customization work and I need to again change mode production to default so is it possible in Magento 2 ?|

If not then what to do for customization in production mode?

and what to do for fast loading pages into Magento 2 in default mode?

Please suggest me

[kgerasimov · Accepted solution]

You can change production mode to default mode with no problems. Just run

php bin/magento deploy:mode:set default

or

php bin/magento deploy:mode:set developer

Now as for Magento 2 Optimization in default mode. First make sure you set Merge,Bundle and Minify CSS/JS to No. Setting it to Yes in default mode can slow down the site.

A fresh copy of M2 is usually pretty fast in default or developer mode. If yours is slow then you need to do TTFB (time to first byte) audit. Fire up Magento 2 profiler and analyze its trace. Maybe there is an extension that slows you down. You need to find it.

To enable Magento 2 profiler simply add to index.php ( or pub/index.php ):

$_SERVER['MAGE_PROFILER'] = 'html';

And you will see trace at the bottom of a frontend page.