Drupal modules and its impact on performance

Up until yesterday I still think that the more modules you install on Drupal, the slower the website will be. And I was wrong (doh!). After I install various modules to enhance website functionality, I try to measure its performance using my regular tools, YSlow and PageSpeed. With 17 modules installed (listed here) I found that the performance is still pretty good.
YSlow Grade: B, Score: 86
PageSpeed Score: 94

Fast and its consequences

After my last post last year, seems like my website going pretty fast. But I just realized its consequences, the CSS is gone and the appearance goes plain, black and white. It appears there are problems with the settings on Configuration-Development-Performance menu which resulted in missing CSS. The second problem is Administration menu module. This really helpful menu suddenly gone and only display Wrench icon on the top left corner. After turning off both Aggregrate CSS and Javascript both problems are gone.

Bandwith Optimatization on Drupal 7

This experiment is to test some Bandwith Optimization parameter on Drupal 7 and its impact on website performance. The impact was measured using Firefox's plugin YSlow and Page Speed. The initial benchmark is as follow:

Drupal 7 with standard configuration/fresh install:
YSlow Rating : Grade B (80) - 183.9K
Page Speed Score : 74/100

First, Aggregate Javascript Page option is checked, the results are:

YSlow Rating : Grade B (87) - 87.2K
Page Speed Score : 84/100