TWS option chain updates "impl bid vol" and "impl ask vol" slowly and incorrectly

See screenshot. The 7 put bid was 0.4, and I put in a big bid at 0.5, and the impl bid vol took a minute or two to change, and I still doubt it's correct because it only went from 97 to 102 while the ask is still 0.55 and its ivol went from 112 to 117.
upload_2020-12-30_9-15-11.png


Using the real time price feeds it'd be trivial for TWS to calculate its own ivols client-side in real time. Why doesn't it do that?
 
See screenshot. The 7 put bid was 0.4, and I put in a big bid at 0.5, and the impl bid vol took a minute or two to change, and I still doubt it's correct because it only went from 97 to 102 while the ask is still 0.55 and its ivol went from 112 to 117.
View attachment 247709

Using the real time price feeds it'd be trivial for TWS to calculate its own ivols client-side in real time. Why doesn't it do that?
guessing that they don't dare change anything and also no incentive to fix it
 
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