Lecture Notes about performance of websites, how to measure it and improve it as a Web developer.
It has a summary section on the left side of the page, following the Cornell note taking method, where the key points are summarised on the side of the noted.
Performance Contents
optimisation leads Performance Trade-off
to extra cost, time, Frontend vs Backend
new bugs and Performance
more obscure Measuring
Improve Progressive Rendering
code
Delays vs User Perception
Backend: Stylesheets
compiler, Scripts
database, memory Less Download Time
management, new Distance to Server
hardware Components
Use Ajax
Front end causes Fewer HTTP Requests
80% of issues Cache More
Add Expires Header
Performance is
JS/CSS Inline vs External
measured by:
External
human Duplicate or Unused scripts
observation Remove Duplicate Scripts
Summary
logging code
and time
profiling using Performance Trade-off
automation, to Optimising for performance might lead to
find
extra cost or time
bottlenecks
new bugs being introduced
Improvements:
more obscure code
Progressive
rendering
renders the
Performance 1
, content as
soon as ‼️ We need to understand the compromise,
possible ensure change is a worthy improvement
stylesheets
should be
at the top Frontend vs Backend
scripts
Backend
should be
at the compiler optimisation options
bottom, database indexes and application
because architecture
they block
memory management
parallel
downloading new hardware
Less download Front end issue: 80% of total time
time
Small changes, great boost in performance
distance to
the server:
use CDNs Performance
to reduce
physical
distance
‼️ Do not waste time trying to speed up code
that does not consume a significant amount
Components of the time
need to be
downloaded at
only 10-20% of the end user response time
least once and
is spent downloading the HTML document
they may
The other 80-90% is spent downloading all
change a lot
the components in the page
using gzip
compresses
the Measuring
component
and Human observation: use the application on your
reduces target platforms and ensure the performance is
download adequate
time
Performance 2
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