Chrome dev tools showing high cache storage utilis

Question

I was analyzing the service workers and cache storage we have implemented in our website.

Going through the process, I found out that the amount of cache storage used by the website is huge.

The cumulative size of the files that I am adding to cache storage is not more than 5-6 MB. But in the chrome dev tools, it shows approximately 130 MB storage used.

chrome - v 63 .
OS - osx

In incognito mode it shows usage as high as 100 MB which causes Quota Exceeded error .

Even after clearing browsing data from chrome settings, and reloading the webpage (bandwidth speed - 1MBps) , just after 4-5 seconds the storage use is shown as 130 MB which is practically not possible because

1) As mentioned above my actual data size added to cache is 5-6 MB .

2) even if it was somehow getting 130 MB (i don't know how), downloading 130 MB is just not possible given my bandwidth limitations.

What might be the issue here ? Why does it show such high cache storage usage?