Along with engine partner Mercedes, Aston Martin is among the teams most impacted by porpoising.
While some rivals have dialled it out and Ferrari appears to be able to deal with it without compromising performance, Aston Martin has been obliged to raise the ride height of the car, taking it out of the optimum aerodynamic window.
"I think we cannot explore the aero potential that the car is having due to the porpoising," said Krack.
"And this puts like a virtual barrier on how far we can go. So we cannot extract the performance that the car is really having, this is the main problem."
Krack says that the car will be improved in a "couple of races", implying that updates are coming for the Spanish GP in Barcelona.
However, he is reluctant to be too tied to a public declaration of when new parts are scheduled to hit the track, and what impact they are likely to have.
"I think in a couple of races we will be in better shape," he said. "It would be foolish to say, in race X or race Y, because even if you bring new parts on, you always need to understand them.
"And you need to understand what job you have done. So say, for example, we bring a big package to Miami, and there is rain or whatever, and we don't make it work.
"You create a lot of expectations, and then everybody will consider you have failed. Take the sprint [at Imola], we have only one session on Friday, you bring a big update, and you have no chance at all to test it, or to validate if it works or not.
"From that point of view, I think it's very important not to say a specific event, especially to the outside world. I mean, we have our internal plans, you will understand that I don't want to go into detail there. But I think in a couple of races we should be in better shape."
Krack says the team prefers to bring regular small updates rather than commit to a major package.
"For us we want to bring updates every race, so we want to have a continuous development, and bring updates all the time.
"Sometimes they are a bit bigger, sometimes they are a bit smaller, but it's important to keep the development alive and not stop.
"Obviously at one point in the season you have to stop and focus on the next year's car, but we are quite far from that at the moment."
After the team suffered four accidents over the Melbourne weekend, Krack was concerned that updates planned for Imola would have to be postponed due to a manufacturing focus on replacing damaged parts
However, in the end the team did get the new items made in time.
"We managed basically with a huge effort from the team in Silverstone to not delay the upgrade, and still have spares. We cannot do this every week either. Because otherwise, it's just immense, what hasn't been achieved."
Regarding the impact of crashes on the budget cap, he added: "We have to worry, the accidents always figure in your calculation. So you must not have these every race, because otherwise you end up on the deep red very early.
"So yeah, we have this on the radar. It is still under control. There is provision for such stuff, but it must not happen every race."