isearch-lazy-highlight-initial-delay

isearch-lazy-highlight-initial-delay is a variable defined in `isearch.el'.
Its value is

0.25

• This variable is an alias for `lazy-highlight-initial-delay'.
• This variable is obsolete since 22.1;
  use `lazy-highlight-initial-delay' instead.

Documentation:
Seconds to wait before beginning to lazily highlight all matches.

You can customize this variable.