The delay within the charts may be due to the overall number of open charts or to the number of open charts displaying the same contract. What may help is either reducing the number of overall charts open or the number of the charts showing data for the same contracts.
More information on why your chart is delayed, showing question marks, or is only partially populated can be found in our Knowledge Base.
If the issue is affecting TWS overall and not only the charts, please see: Are there ways to optimize my TWS configuration to improve performance?