You need to use the reserve function to set an initial allocated size or do it in the initial constructor.
vector<CustomClass *> content(20000);
or
vector<CustomClass *> content;
...
content.reserve(20000);
When you reserve()
elements, the vector
will allocate enough space for (at least?) that many elements. The elements do not exist in the vector
, but the memory is ready to be used. This will then possibly speed up push_back()
because the memory is already allocated.