Adding a new member in struct sk_buff - any impact on performance?

I need to add one small buffer to sk_buff structure and want add it as separate member or adding it on top of default skb->cb.

The size will be around 100 bytes. Here, the concern is "performance". Can it result in any performance hit for packet processing? Especially, cache alignment, as an sk_buff of this size cannot be loaded in a single cache line, could that cause issues?

I did an experiment where I simply added 4 more bytes in sk_buff, and noticed that there was 30-50MBps performance drops in regular UDP tests.

Any advice?