The maritime sector has gained significant experience in complying with regulations supporting global decarbonization and reducing greenhouse gas emissions from shipping. Key instruments driving this transition are the International Maritime Organization's (IMO) Energy Efficiency Design Index (EEDI), Energy Efficiency Existing Ship Index (EEXI), and Carbon Intensity Indicator (CII). While many studies address individual vessels or small fleets, large-scale analyses combining all three indices remain scarce, especially for container ships, which play a major role in global trade. This study reviews existing literature on compliance and the effectiveness of technical and operational measures for container ships, then evaluates 162 vessels built between 2000 and 2020, from small feeders to ultra-large container ships (ULCS). The analysis includes EEDI and EEXI for all vessels and CII for 21, examining trends in key design parameters. Results show that most ships initially met EEDI limits, but compliance has declined, while EEXI and CII performance remain considerably lower. The main adaptation strategy is slow steaming, with an average speed reduction of 33%. Overall, findings suggest that future compliance with IMO decarbonization goals will require major design changes and the adoption of alternative fuels, as existing technical and operational measures are nearing their limits.