Nowadays, the development of products for modern cyber-physical systems consists of many stages defined by the product life cycle (PLC). However, many manufacturers are not paying full attention - if any at all - to each PLC stage. This, among others, is causing growth of development costs. Therefore, the first stage of PLC becomes crucial. Moreover, a significant part of the development costs might be saved via testing the required parameters in this early stage, e.g., via modeling tools, simulation tools or emulators. Considering among others the current cyber-warfare and everyday growing number of threats, security is becoming one of the most critical topics in PLC. However, the security aspects come with significant trade-offs with performance. This paper focuses on methodology for dealing with these trade-offs via simulation in the early stage of PLC, where basic requirements are settled. To establish security requirements, an extensive Secure Software Development Life Cycle catalog is used together with an advanced modeling framework TTool based on UML/SysML-Sec for performance trade-off analysis. This combination creates a powerful approach for establishing the balance between security and performance requirements. As an example, a particular security requirement is selected. Namely, confidentiality, fulfilled by the encryption algorithm AES. This introduces the methodology and approach to the co-engineering issue in the PLC stages, where two different development teams with also different goals (security, performance) are dealing together with the single combined issue. Our results should help to understand the importance of the early PLC stage and show one possible approach on how to deal with these issues.