You might have seen ample number of blogs, information and other resources out there that talk about the same topic. But, I will try and make this in steps, so you have step-by-step guide all in here and you will surely spend less time scraping this data from 10 other places.
At the end, I will also list references on where I gathered all this from, so, you can refer and read more if you are an enthusiastic reader.
Have you heard about Google page speed extension? If you did not, it is fine and I will not say you were living in a cave, in this functional desire world, I wonder why performance is always addressed at the very end of the tunnel in software life cycle. I would go ahead and say a simple performance test plan should be part of every step of implementation. It could be simple, but invasive. It would help mitigate surprises which usually take time to resolve.
There are tons of tools out there as well to measure performance, but, I got hooked on to Google page speeds extension as it is easy to visualize and Google does do a good job of providing links to problems that were uncovered which would provide good insight to multiple solutions to the problem on hand.
Let us get this started –
1. First do not expect anything, don’t assume that your site is great or worst in terms of performance. Just download the extension of your favorite choice, I like the Google Page Speeds extension, but, you could run anything
2. Address to one’s Google put’s more weight on and are in red. I think that would be the critical one’s for sure. I did the following and saw immediate boost on numbers
Images and Images (Scaling and Optimization)
Firstly ensure you are scaling images on server side (Using Glass params) instead of depending on content authors to upload files of certain dimensions. Though we tried to enforce this through documentation and collaboration, we still saw lapse.
Best way to battle this is use Glass params, then, regardless of whether recommended size is respected or not, your browser will not spend ton of time sizing and re-sizing images to fit your FEE needs(css)
Get the params based on FEE recommendations, the best thing to do is set width and let height be auto.
After these steps, please follow sitecore performance tuning guide no less than Bible(link in references), go over all content delivery preferences and ensure you set all of them correctly. When in question about something please check with your support team.
That is it, you just made your sitecore instance super efficient. The tuning guide should also cover caching best practices which should bump up good performance benefit second load on wards.
Happy Sitecoring!!
Few Good References
https://developers.google.com/speed/pagespeed/insights/
https://sdn.sitecore.net/upload/sitecore7/70/cms_tuning_guide_sc70-72-usletter.pdf
https://chrome.google.com/webstore/detail/google-pagespeed-insights/edbkhhpodjkbgenodomhfoldapghpddk?hl=en
https://developers.google.com/speed/docs/insights/EnableCompression