When comparing Bottle vs Phalcon, the Slant community recommends Phalcon for most people. In the question“What are the best backend web frameworks?” Phalcon is ranked 10th while Bottle is ranked 20th. The most important reason people chose Phalcon is:
Since the framework is and extension built in C it's extremely fast and efficient. It's actually one of the fastest PHP frameworks, and according to some benchmarks it's the fastest framework out there.
Specs
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Pros
Pro Flexible
Being a small one file distribution it includes almost every vital thing you need to support little websites (routing, templating). Everything else can be implemented using plugins.
Pro Single-file distribution
Bottle works around the one-file approach, everything is done in a bottle.py
file. This means that it's extremely easy to share and upload your application since it practically is just one python file.
Pro No need to install
It is so little there's no need to install, it is included in the standard libs python.
Pro Async, *let friendly
Using it with gevent is a breeze. It's a WSGI app so it's easy to make it work with anything.
Pro Truly magnificent
Pro Extremely fast
Since the framework is and extension built in C it's extremely fast and efficient. It's actually one of the fastest PHP frameworks, and according to some benchmarks it's the fastest framework out there.
Pro Open source
Phalcon is open source and is available under the BSD License.
Pro Uses Volt template engine
The Volt template engine, which is embedded into Phalcon itself takes it's inspiration from the Jinja template engine and as such it's nice to look at, with a clear and understandable syntax.
Volt also compiles very fast, like Phalcon itself, so it avoids being a bottleneck for the framework's overall speed.
Pro Very flexible project structure
You can set up the base project as you want. It's very flexible
Pro Clean and light project code
Since the framework code is not in the project directory, the code is light and clean.
Pro Customizable with Zephir
Zephir is a high-level language designed to create PHP extensions easily by PHP programmers with no knowledge in C.
Zephir does this by compiling directly to C and then the C program is in turn compiled to be run as a PHP extension. This, coupled with the fact that Zephir's syntax is very similar to PHP makes it a perfect way for PHP developers to use it for customizing Phalcon.
Pro Loosely coupled components
Some components can be used as standalone packages like models, views, etc..
Cons
Con Small community. Difficult to find online docs and examples
Con Very hard to develop projects that are not smaller than 1000 lines
While Bottle is a great framework for building small applications (generally less than 1000 lines of code), it starts getting very hard to manage your application if you want to go even a bit larger than that.
The fact that it follows a single-file distribution model and that it's missing something like Flask's blueprints only make this problem worse.
Con Not for shared hosting
Phalcon needs root access to install the PHP extension which is written in C. Developers who plan on using Phalcon must use VPS or Cloud Hosting with root access available.
Con Require good programming skills
Not so easy to use if you want to gain the best from it.
Con Debugging requires knowledge of C
You need to be a C programmer to debug Zephir or C code. Or if Phalcon is not maintained anymore and you have a problem and don't have much skills in C, you will be hard-pressed to find a C programmer to fix it.