Suddenly takes forever to open browser & Google play store

My Blue Studio HD 6.0 was working great then suddenly slowed to a crawl. It takes forever to open any page in browser. Google Play Store sometimes is so slow it won't open at all, takes literally hours to download & install app updates & some now won't update at all. I tried to install wireless update several times, after 30 minutes to download the update and trying to install i get message that update.zip is corrupted and install was aborted. PLEASE HELP! REALLY LOVED THIS PHONE & NOW ITS BARELY USABLE.