drawn-out 
adjective
Lasting or seeming to last longer than is necessary: after the long drawn-out years of waiting the end of the war was in sight...
- Since then, the necessary drawn-out processes added to the personal anguish that he's clearly suffered.
- The fourth is the slow, drawn-out demise of Soho itself.
- And by this point, the process became so slow and drawn-out that they were ineffective.