How can I use break or continue within for loop in Twig template?

From docs TWIG 2.x docs:

Unlike in PHP, it's not possible to break or continue in a loop.

But still:

You can however filter the sequence during iteration which allows you to skip items.

Example 1 (for huge lists you can filter posts using slice, slice(start, length)):

{% for post in posts|slice(0,10) %}
    <h2>{{ post.heading }}</h2>
{% endfor %}

Example 2 works TWIG 3.0 as well:

{% for post in posts if post.id < 10 %}
    <h2>{{ post.heading }}</h2>
{% endfor %}

You can even use own TWIG filters for more complexed conditions, like:

{% for post in posts|onlySuperPosts %}
    <h2>{{ post.heading }}</h2>
{% endfor %}

This can be nearly done by setting a new variable as a flag to break iterating:

{% set break = false %}
{% for post in posts if not break %}
    <h2>{{ post.heading }}</h2>
    {% if post.id == 10 %}
        {% set break = true %}
    {% endif %}
{% endfor %}

An uglier, but working example for continue:

{% set continue = false %}
{% for post in posts %}
    {% if post.id == 10 %}
        {% set continue = true %}
    {% endif %}
    {% if not continue %}
        <h2>{{ post.heading }}</h2>
    {% endif %}
    {% if continue %}
        {% set continue = false %}
    {% endif %}
{% endfor %}

But there is no performance profit, only similar behaviour to the built-in break and continue statements like in flat PHP.