About couchbase hit rates question

for example, my key = ‘key’, value = ‘value’, and get(key), the web console show me ops per second is 5K, and i change value = ‘value’*1000, and get(key), the web console show me ops second is 200, when the value is so huge , the hit rates will lower,how can i improve the hit rates when value is a huge value, thank you very much